1
The probability of heads on one coin is —
💡 Hint:
Two outcomes.
Explanation:
1/2.
Class 10 · Maths · Chapter 14 · बिहार बोर्ड (BSEB)CBSE · NCERT 2026-27
Probability
Probability
How to use this page:
1. Read — Equally likely outcomes · P(E) · complementary event · Exercise 14.1, diagram, worked example, board tip
2. Check — each lesson has its own questions; the number follows the lesson
3. Mastery ★ — all of that lesson correct. Redo the wrong ones
4. The memory figure shows probability on a strip from 0 to 1, with the impossible event, an event and the sure event.
In NCERT 2026-27 this is Chapter 14; in Bihar’s older book Probability is Chapter 15. Progress stays in this browser.
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- 1 Equally likely outcomes
- 2 P(E) and an elementary event
- 3 0, 1 and the complement
- 4 Coins, an arrow and a fish
- 5 A die and a pack of cards
- 6 Without putting it back
- 7 Two dice and a faulty argument
- Chapter winner — every lesson at mastery ★
🎬 Shorts
This chapter has no Short on the channel yet, so ten empty cards are not shown. The notes, diagrams and checks are complete.
📄 PDF download — notes + answer key
Equally likely outcomes
समप्रायिक परिणाम · Opening of NCERT 14.1 · questions 2 and 3
The same hope for every outcomeNotes
A fair coin is symmetrical. In a random toss, heads and tails are equally likely. The book does not count landing on the edge.
The six faces of a die are equally likely. A car starting, or a basketball shot landing, is not equally likely. The book treats a true-false guess and the birth of a boy or a girl as equally likely. In question 3 the coin is fair because there is no tilt toward either side.
The list first, then equal or notActivity
Write the names of the outcomes. If practice, weather or skill tilts one side, do not call them equally likely. In a bag of 4 red balls and 1 blue ball, red and blue are not equally likely. Drawing any one particular ball is equally likely.
Worked exampleExample
Question: A coin is tossed once. The probability of heads.
Formula: P = favourable / total, when the outcomes are equally likely.
Substitution: Favourable 1, total 2. 1/2.
Answer: 1/2. The probability of tails is also 1/2.
10-second revision
- Heads and tails are both 1/2
- One face of a die is 1/6
- A game of skill is not equally likely
Board tip · BSEBBoard tip
In a BSEB answer write yes or no for question 2 with one reason.
Board tip · CBSEBoard tip
On CBSE do not call 4 red and 1 blue equally likely.
Check your understandingall correct = mastery ★
2
A basketball shot landing or missing is treated as equally likely.
Explanation:
False — skill tilts it.
3
The probability of one face of a die is ______.
💡 Hint:
Six faces.
Explanation:
1/6.
4
A random answer to a true-false question is —
💡 Hint:
Question 2 (iii).
Explanation:
Equally likely.
5
Why is a car starting not equally likely?
Model answer (board format)
Starting depends on the battery and the engine. Starting and not starting are not given equal hope.
Check your answer:
P(E) and an elementary event
P(E) और प्राथमिक घटना · The definition · lines 1 and 5 of the summary
The favourable share of the wholeNotes
An event is a group of one or more outcomes. An event with only one outcome is an elementary event.
P(E) = favourable outcomes / total equally likely outcomes. The probabilities of the elementary events add to 1. A die has six elementary events and 6 × (1/6) = 1.
The same total under every fractionActivity
Three red and five black balls make 8. Red is 3/8, black is 5/8. The bottom of the fraction stays 8 every time. The top changes. Writing 3/5 treats the total as the black balls.
Worked exampleExample
Question: The probability of one red ball from 3 red and 5 black.
Formula: P = favourable / total.
Substitution: Favourable 3, total 8. 3/8.
Answer: 3/8. Not red, that is black, is 5/8.
10-second revision
- The bottom is the total
- 3/8 and 5/8
- Elementary events add to 1
Board tip · BSEBBoard tip
In a BSEB answer write favourable and total on two short lines.
Board tip · CBSEBoard tip
On CBSE turn a fraction into a decimal only when the question asks. Leave 3/8 as it is.
Check your understandingall correct = mastery ★
1
With 3 red and 5 black, the probability of red is —
💡 Hint:
The total is 8.
Explanation:
3/8.
2
The probabilities of the elementary events add to 1.
Explanation:
True — line 5 of the summary.
3
A die has ______ elementary events.
💡 Hint:
Six faces.
Explanation:
6.
4
The probability of a black ball is —
💡 Hint:
5 favourable.
Explanation:
5/8.
5
An elementary event holds many outcomes at once.
Explanation:
False — it holds one outcome.
6
From 5 red, 8 white and 4 green marbles, write the probabilities of white and of not green.
Model answer (board format)
The total is 17. White is 8/17. Not green is 13/17.
Check your answer:
0, 1 and the complement
0, 1 और पूरक · Exercise 14.1 questions 1, 4, 5, 6, 7
Nothing sits outside the stripNotes
An impossible event has probability 0. A sure event has 1. Every event between them lies between these.
P(E) + P(not E) = 1. In a bag of only lemon candies, orange is 0 and lemon is 1. If P(E) = 0.05, then not E = 0.95. If not sharing a birthday is 0.992, sharing one is 0.008. −1.5 cannot be a probability.
Subtract from 1Activity
The complement is not a fresh count when one probability is already given. 1 − 0.05 = 0.95. 1 − 0.992 = 0.008. Turn a percent into a decimal first: 15 percent = 0.15, and that is allowed.
Worked exampleExample
Question: P(E) = 0.05. Find P(not E).
Formula: P(not E) = 1 − P(E).
Substitution: 1 − 0.05 = 0.95.
Answer: 0.95.
10-second revision
- 0 impossible, 1 sure
- The complement of 0.05 is 0.95
- −1.5 is rejected
Board tip · BSEBBoard tip
In a BSEB answer complete the five blanks of question 1 one by one.
Board tip · CBSEBoard tip
On CBSE do not pick 15 percent as the impossible number. Pick −1.5.
Check your understandingall correct = mastery ★
1
This cannot be a probability —
💡 Hint:
A negative.
Explanation:
−1.5.
2
In a bag of only lemon candies, the probability of orange is 0.
Explanation:
True — impossible.
3
If P(E) = 0.05, then P(not E) = ______.
💡 Hint:
1 − 0.05.
Explanation:
0.95.
4
The probability that two students do not share a birthday is 0.992. Find the probability that they do.
Model answer (board format)
1 − 0.992 = 0.008.
Check your answer:
Coins, an arrow and a fish
सिक्के, तीर और मछली · Exercise 14.1 questions 10, 11 and 12
Add the total firstNotes
The piggy bank has 100 fifty-paise coins, 50 one-rupee coins, 20 two-rupee coins and 10 five-rupee coins. The total is 180 coins.
Fifty paise is 100/180 = 5/9. Not a five-rupee coin is 170/180 = 17/18. The fish are 5 male and 8 female, total 13, so male is 5/13. The arrow stops on 1 to 8. The probability of 8 is 1/8, and a number less than 9 is sure, probability 1.
Count odd and greater than 2 apartActivity
From 1 to 8 the odd numbers are 1, 3, 5 and 7, four of them. The probability is 4/8 = 1/2. Greater than 2 are 3, 4, 5, 6, 7 and 8, six of them. The probability is 6/8 = 3/4. The number 2 itself is not in that list.
Worked exampleExample
Question: Of 180 coins, 100 are fifty paise. One coin falls out. The probability it is fifty paise.
Formula: P = 100/180.
Substitution: 100/180 = 10/18 = 5/9.
Answer: 5/9.
10-second revision
- 180 coins in all
- Fifty paise is 5/9
- 8 on the arrow is 1/8
Board tip · BSEBBoard tip
In a BSEB answer write the addition line for the total 180 first.
Board tip · CBSEBoard tip
On CBSE do not write 0 for a number less than 9. The arrow only goes to 8, so this is 1.
Check your understandingall correct = mastery ★
1
Among 180 coins, the probability of fifty paise is —
💡 Hint:
100/180.
Explanation:
5/9.
2
On the arrow, the probability of a number less than 9 is 1.
Explanation:
True — all eight numbers are less than 9.
3
The probability of a male fish is ______.
💡 Hint:
5 and 8.
Explanation:
5/13.
4
The probability of an odd number on the arrow is —
💡 Hint:
Four odd numbers.
Explanation:
4/8 = 1/2.
5
Find the probability that a five-rupee coin does not fall out. Total 180, and there are 10 such coins.
Model answer (board format)
170/180 = 17/18.
Check your answer:
A die and a pack of cards
पासा और ताश · Exercise 14.1 questions 13 and 14
52 cards, four suitsNotes
A pack has 52 cards. Each suit has 13. Jack, queen and king are the face cards, 12 in all. Red face cards are 6.
On a die the primes are 2, 3 and 5, probability 3/6 = 1/2. Between 2 and 6 are 3, 4 and 5, again 1/2. A red king is 2/52 = 1/26. A spade is 13/52 = 1/4. One named card is 1/52.
Look at face and colour togetherActivity
A red face card demands both conditions. Half of the 12 face cards are red, so 6/52 = 3/26. A face card alone is 12/52 = 3/13. The jack of hearts is one card, 1/52.
| Ask | Favourable | Probability |
|---|---|---|
| Red king | 2 | 1/26 |
| Face card | 12 | 3/13 |
| Red face | 6 | 3/26 |
| Spade | 13 | 1/4 |
Worked exampleExample
Question: The probability of a spade from a well-shuffled pack.
Formula: P = 13/52.
Substitution: 13/52 = 1/4.
Answer: 1/4.
10-second revision
- A prime has probability 1/2
- A face card is 3/13
- One named card is 1/52
Board tip · BSEBBoard tip
In a BSEB answer write 52 under every fraction and then simplify.
Board tip · CBSEBoard tip
On CBSE do not forget the queen and the king apart from the jack. Face cards are of three kinds.
Check your understandingall correct = mastery ★
1
The probability of a prime on a die is —
💡 Hint:
2, 3, 5.
Explanation:
3/6 = 1/2.
2
The probability of a spade is 1/4.
Explanation:
True — 13/52.
3
The probability of a red king is ______.
💡 Hint:
Two red kings.
Explanation:
1/26.
4
The probability of a face card is —
💡 Hint:
12/52.
Explanation:
3/13.
5
The king of diamonds and a red king are the same count.
Explanation:
False — there are two red kings.
6
Write both probabilities: the jack of hearts, and a red face card.
Model answer (board format)
The jack of hearts is 1/52. A red face card is 6/52 = 3/26.
Check your answer:
Without putting it back
बिना वापस रखे · Exercise 14.1 questions 15, 16, 17 and 18
The second time, the total fallsNotes
From five cards the queen is 1/5. Remove the queen and four cards remain. An ace is 1/4 and a queen is now 0.
Pens are 12 bad + 132 good = 144. Good is 132/144 = 11/12. Bulbs are 4 bad and 16 good. After a good one is drawn and not replaced, 15 of the remaining 19 are good. A good bulb is 15/19. Among discs 1 to 90, two-digit numbers are 81/90 = 9/10.
Do not count the removed card againActivity
The first queen was favourable and is no longer in the set. The second time, the probability of a queen is 0. The ace is still one, but the total has become 4. In a without-replacement question, write the two totals apart.
Worked exampleExample
Question: Of 20 bulbs, 4 are bad. A good one is drawn and not replaced. The probability of a good bulb now.
Formula: P = good left / total left.
Substitution: There were 16 good. After one good is removed, 15. Total 19. 15/19.
Answer: 15/19.
10-second revision
- The second queen has probability 0
- A good pen is 11/12
- The next good bulb is 15/19
Board tip · BSEBBoard tip
In a BSEB answer write the totals of the first and second draws apart.
Board tip · CBSEBoard tip
On CBSE do not write 16/19. A good bulb has already left, so 15 remain.
Check your understandingall correct = mastery ★
1
After the queen is removed, the probability of a queen is —
💡 Hint:
That card has gone.
Explanation:
0.
2
Among 144 pens, the probability of a good pen is 11/12.
Explanation:
True — 132/144.
3
The probability of the next good bulb is ______.
💡 Hint:
15 good left, total 19.
Explanation:
15/19.
4
Find the probability of a perfect square on discs numbered 1 to 90.
Model answer (board format)
The squares are 1, 4, 9, 16, 25, 36, 49, 64 and 81. Nine discs. 9/90 = 1/10.
Check your answer:
Two dice and a faulty argument
दो पासे और गलत तर्क · Exercise 14.1 questions 22 to 25 · summary
There are fewer names than outcomesNotes
Two dice have 36 ordered outcomes. The sum 7 can happen in six ways, probability 6/36 = 1/6. Calling the eleven sums 1/11 is wrong.
Three coins have 8 outcomes. All three alike happens in only two ways, so the loss is 6/8 = 3/4. A die thrown twice is the same experiment as two dice. No 5 at all has probability 25/36. On two coins, one of each has probability 1/2, not 1/3. The argument that an odd number is 1/2 is correct.
Order is a different outcomeActivity
Head-tail and tail-head are two outcomes. Do not fold them into one name and make three outcomes. On two dice, (1,2) and (2,1) are different too. Question 20 is about area, and the book does not count it for the examination.
Worked exampleExample
Question: A die is thrown twice. The probability of at least one 5.
Formula: P(at least one) = 1 − P(none).
Substitution: Not 5 once = 5/6. Twice, (5/6)×(5/6) = 25/36. 1 − 25/36 = 11/36.
Answer: 11/36.
10-second revision
- Two dice = 36 outcomes
- The sum 7 has probability 1/6
- At least one 5 has probability 11/36
Board tip · BSEBBoard tip
In a BSEB answer show a small part of the table of 36, not all 36 lines.
Board tip · CBSEBoard tip
On CBSE do not accept the arguments that use 1/11 and 1/3. Count the outcomes.
Check your understandingall correct = mastery ★
1
The probability of sum 7 on two dice is —
💡 Hint:
Six ways, total 36.
Explanation:
6/36 = 1/6.
2
On two coins, the probability of one head and one tail is 1/3.
Explanation:
False — 2/4 = 1/2.
3
On three coins, the probability of losing is ______.
💡 Hint:
6 out of 8.
Explanation:
3/4.
4
The argument that an odd face on a die has probability 1/2 is —
💡 Hint:
Three odd, three even.
Explanation:
Correct. Question 25 (ii).
5
A die is thrown twice. Write the probability of no 5 either time and of at least one 5.
Model answer (board format)
No 5: 25/36. At least one 5: 1 − 25/36 = 11/36.
Check your answer:
❓ Full question bank — with answers and explanations — 65 questions
Pick a type. The 35 lesson checks are separate — each lesson has as many as its topic needs. All correct earns mastery ★.
BSEB modelpractice · not annual60 tried · 0 correctMultiple choiceMCQ120 tried · 0 correctTrue / falseTrue / false80 tried · 0 correctFill in the blanksFill80 tried · 0 correctMatchMatch20 tried · 0 correctAssertion–reasonAssertion–reason50 tried · 0 correctBalancingBalancing40 tried · 0 correctIdentifyIdentify20 tried · 0 correctShort and longVSA, SA, LA120 tried · 0 correctCBSE-stylenot a PYQ60 tried · 0 correct
No question is marked as a verified past paper. The BSEB set is a model for practice. CBSE items are CBSE-style, not a copy of any year’s paper.
Multiple choice
0/12Pick one option. A wrong try brings a hint.
1
Heads on one coin is —
💡 Hint:
Two outcomes.
Explanation:
1/2.
2
This is not a probability —
💡 Hint:
Negative.
Explanation:
−1.5.
3
Red among 3 red and 5 black is —
💡 Hint:
Total 8.
Explanation:
3/8.
4
If P(E) = 0.05, not E is —
💡 Hint:
Subtract from 1.
Explanation:
0.95.
5
The probability of fifty paise is —
💡 Hint:
100/180.
Explanation:
5/9.
6
A male fish is —
💡 Hint:
Total 13.
Explanation:
5/13.
7
A spade is —
💡 Hint:
13/52.
Explanation:
1/4.
8
A good pen is —
💡 Hint:
132/144.
Explanation:
11/12.
9
The sum 7 is —
💡 Hint:
6/36.
Explanation:
1/6.
10
At least one 5 is —
💡 Hint:
1 − 25/36.
Explanation:
11/36.
11
Losing on three coins is —
💡 Hint:
6/8.
Explanation:
3/4.
12
The next good bulb is —
💡 Hint:
One good one has left.
Explanation:
15/19.
True or false
0/81
A basketball shot is equally likely.
Explanation:
False.
2
An impossible event has probability 0.
Explanation:
True.
3
−1.5 is a probability.
Explanation:
False.
4
Elementary events add to 1.
Explanation:
True.
5
On two coins, one of each has probability 1/3.
Explanation:
False — 1/2.
6
Two dice have 36 outcomes.
Explanation:
True.
7
After the queen is removed, a second queen has probability 0.
Explanation:
True.
8
The argument that an odd face has probability 1/2 is wrong.
Explanation:
The statement is false — that argument is correct.
Fill in the blanks
0/81
The probability of heads is ______.
💡 Hint:
1/2.
Explanation:
One over two.
2
The complement of 0.05 is ______.
💡 Hint:
0.95.
Explanation:
1 − 0.05.
3
The probability of a shared birthday is ______.
💡 Hint:
0.008.
Explanation:
1 − 0.992.
4
A red ball is ______.
💡 Hint:
3/8.
Explanation:
3 and 5.
5
A spade is ______.
💡 Hint:
1/4.
Explanation:
13/52.
6
A square disc is ______.
💡 Hint:
1/10.
Explanation:
Nine squares.
7
No 5 is ______.
💡 Hint:
25/36.
Explanation:
(5/6)×(5/6).
8
Fifty paise is ______.
💡 Hint:
5/9.
Explanation:
100/180.
Match
0/21
Match the event with the probability.
Column B: A. 1/2 · B. 1 · C. 0 · D. 1/6
1. Sure
2. Impossible
3. One die face
4. Heads
Explanation:
Sure is 1, impossible is 0, a face is 1/6, heads is 1/2.
2
Match the question with its answer.
Column B: A. 11/36 · B. 0.95 · C. 3/8 · D. 1/4
1. Question 5
2. Question 8 red
3. Question 14 spade
4. Question 24 at least one 5
Explanation:
The complement in 5 is 0.95, red is 3/8, a spade is 1/4, and at least one 5 is 11/36.
Assertion–reason
0/5Check both statements, then see whether the reason explains the assertion.
1
Assertion (A): If P(E) = 0.05, the probability of not E is 0.95.
Reason (R): Complementary events add to 1.
Explanation:
Both are true and R explains A.
2
Assertion (A): −1.5 is a possible probability.
Reason (R): Probability stays between 0 and 1, ends included.
Explanation:
A is false. R is true.
3
Assertion (A): On two dice the probability of sum 7 is 1/6.
Reason (R): The 11 names of the sums are equally likely.
Explanation:
A is true. R is false, the ways are spread over 36.
4
Assertion (A): The probability of a spade is 1/4.
Reason (R): The probability of a prime on a die is 1/2.
Explanation:
Both are true, but R does not explain a spade.
5
Assertion (A): After the queen is removed, the probability of another queen is 0.
Reason (R): That one queen has left the set, and four of the five cards remain.
Explanation:
Both are true and R explains A.
Coefficient practice
0/4These chemistry lines are not a result of this maths chapter. They are only practice in filling coefficients. A blank means 1.
1
This is coefficient practice and not a result of this chapter. In the water line, Fill coefficients (blank = 1).
H2 + O2 → H2O
Explanation: 2H2 + O2 → 2H2O
2
This is coefficient practice and not a result of this chapter. In the line of H2 and O2, Fill coefficients (blank = 1).
H2 + O2 → H2O
Explanation: 2H2 + O2 → 2H2O
3
This is coefficient practice and not a result of this chapter. In this coefficient line, Fill coefficients (blank = 1).
H2 + O2 → H2O
Explanation: 2H2 + O2 → 2H2O
4
This is coefficient practice and not a result of this chapter. In the line with blank coefficients, Fill coefficients (blank = 1).
H2 + O2 → H2O
Explanation: 2H2 + O2 → 2H2O
Classify
0/21
Place each number as a kind of probability.
0
1
3/8
−1.5
Explanation:
0 is impossible, 1 is sure, 3/8 is in between, and −1.5 is rejected.
2
Place each experiment as equally likely or not.
A fair coin
A basketball shot
A car starting
A true-false guess
Explanation:
The coin and true-false are equally likely. The shot and the car are not.
Very short answer
0/51
Write the formula for P(E).
Model answer (board format)
Favourable outcomes / total equally likely outcomes.
Check your answer:
2
Write the complement relation.
Model answer (board format)
P(E) + P(not E) = 1.
Check your answer:
3
Why is −1.5 not a probability?
Model answer (board format)
A probability is not smaller than 0.
Check your answer:
4
Write the total outcomes of two dice.
Model answer (board format)
36.
Check your answer:
5
Write the probabilities of a sure event and an impossible event.
Model answer (board format)
Sure is 1, impossible is 0.
Check your answer:
Short answer
0/41
From 3 red and 5 black, find red and not red.
Model answer (board format)
Total 8. Red 3/8. Not red 5/8.
Check your answer:
2
From a pack, find a red king and a face card.
Model answer (board format)
A red king is 2/52 = 1/26. A face card is 12/52 = 3/13.
Check your answer:
3
20 bulbs, 4 bad. A good one is drawn and not replaced. The probability of good now.
Model answer (board format)
Good left 15, total 19. 15/19.
Check your answer:
4
A die twice. No 5, and at least one 5.
Model answer (board format)
25/36 and 11/36.
Check your answer:
Long answer
0/31
Of 180 coins, 100 are fifty paise and 10 are five-rupee. Find both fifty paise and not a five-rupee coin.
Model answer (board format)
Fifty paise is 100/180 = 5/9. Not a five-rupee coin is 170/180 = 17/18.
Check your answer:
2
Two coins are tossed together. Find the probability of one head and one tail, and say why 1/3 is wrong.
Model answer (board format)
Four outcomes: head-head, head-tail, tail-head, tail-tail. Two are favourable. The probability is 1/2. 1/3 treats three names as equal, but one of each is two different outcomes.
Check your answer:
3
Three coins are tossed. A win is all three alike. Find the probability of losing.
Model answer (board format)
The total is 8. The wins are head-head-head and tail-tail-tail, two ways. The loss is 6/8 = 3/4.
Check your answer:
BSEB model paper · practice
0/6This model set is for practice. It is not a question from any year’s annual examination.
1
The probability of a square disc is —
💡 Hint:
Nine squares.
Explanation:
9/90 = 1/10.
2
On the lettered die, the probability of A is —
💡 Hint:
Two A faces, six in all.
Explanation:
2/6 = 1/3.
3
Among 144 pens the probability of a purchase is ______, when 20 are bad.
💡 Hint:
31/36.
Explanation:
124 are good.
4
Find the probability of a disc from 1 to 90 that is divisible by 5.
Model answer (board format)
5, 10, ..., 90. The count is 18. 18/90 = 1/5.
Check your answer:
5
An arrow stops on 1 to 8. Write all four probabilities: 8, odd, greater than 2, and less than 9.
Model answer (board format)
8 is 1/8. Odd is 4/8 = 1/2. Greater than 2 is 6/8 = 3/4. Less than 9 is 8/8 = 1.
Check your answer:
6
Assertion (A): In a bag of only lemon candies, the probability of lemon is 1.
Reason (R): The probability of orange is also 1.
Explanation:
A is true. R is false, orange is 0.
CBSE-style questions
0/6These are competency-based practice questions. They are not a copy of any year’s paper.
1
A student writes 1/3 for one of each on two coins. The correct probability is —
💡 Hint:
Four outcomes, two favourable.
Explanation:
1/2.
2
A student writes 1/11 for the sum 7. The correct probability is —
💡 Hint:
36 outcomes.
Explanation:
6/36 = 1/6.
3
Assertion (A): The probability of odd on a die is 1/2.
Reason (R): There are three odd and three even faces.
Explanation:
Both are true and R explains A.
4
Assertion (A): Question 20 is a compulsory calculation for the examination.
Reason (R): The book writes on that question that it is not from the examination point of view.
Explanation:
A is false. R is true.
5
A student calls 4 red and 1 blue equally likely. How far is that right?
Model answer (board format)
Red and blue are not equally likely, because there are four red balls. Drawing one particular ball is equally likely.
Check your answer:
6
From five cards the queen is drawn and removed. Write the probabilities of an ace and of a queen the second time.
Model answer (board format)
The total is now 4. An ace is 1/4. A queen is 0.
Check your answer:
🏛️ Board exam corner — Bihar Board (BSEB)— CBSE
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CBSE-style · competency-based
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🧠 What you learned + equation sheet
What you learned
- For equally likely outcomes, P(E) = favourable / total.
- A sure event has probability 1 and an impossible event has 0.
- 0 ≤ P(E) ≤ 1.
- P(E) + P(not E) = 1.
- The probabilities of the elementary events add to 1.
- Two dice have 36 outcomes. Do not treat the eleven sums as equal.
| What | Keep this |
|---|---|
| Formula | P(E) = अनुकूल / कुल |
| Sure | P = 1 |
| Impossible | P = 0 |
| Complement | P(E) + P(नहीं E) = 1 |
| Die | एक अंक 1/6 |
| Cards | 52 पत्ते, एक पत्ता 1/52 |
The notes are original writing. The textbook was used only for activity order and numbers. “Verified” will be used only on a question that has a source page.