Chapter 25 · ICSE Class 10 Mathematics (Selina Concise)

Probability

Calculate the probability of simple events, and understand complementary events, deepening the foundation from earlier classes.

🎲 Chapter 25

The sample space of rolling a single die, with the even-numbered outcomes highlighted Six possible outcomes of rolling a die, numbered 1 to 6, with the three even numbers 2, 4, and 6 highlighted to show the probability of rolling an even number is 3 out of 6 1 2 3 4 5 6 P(even number) = 3/6 = 1/2
25.1

Basic Probability Calculations

Probability of an event = (number of favourable outcomes) / (total number of possible outcomes).

1

A bag has 5 red, 3 blue, and 2 green balls. Find the probability of drawing a blue ball.

3/10

2

A die is rolled once. Find the probability of getting a number greater than 4.

Favourable outcomes: 5,6; probability=2/6=1/3

25.2

Complementary Events

The probability of an event NOT happening = 1 − P(event happening). This is useful when it's easier to calculate the complement.

1

The probability of rain tomorrow is 0.3. Find the probability it does not rain.

1−0.3=0.7

2

A card is drawn from a deck of 52. Find the probability it is NOT a heart.

P(heart)=13/52=1/4; P(not heart)=1−1/4=3/4

Practice

Exercises

1. A bag has 4 red, 6 blue balls. Find the probability of drawing a red ball.

2. A die is rolled once. Find the probability of getting an even number.

3. The probability of an event is 0.65. Find the probability of its complement.

4. A card is drawn from a deck of 52. Find the probability it is a king.

5. A card is drawn from a deck of 52. Find the probability it is NOT a king.

🏆🎉 Incredible! You've completed all 25 chapters of ICSE Class 10 Mathematics! 🎉🏆

From Goods & Services Tax to Probability — the entire Class 10 Maths board syllabus is done. Best of luck in your board exams!

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