NCERT solutions

Probability

All 6 textbook questions with direct answer previews. Open any question for simple explanations and exam-ready answers.

All questions

6
Q1

Define theoretical probability of an event.

If all outcomes are equally likely, P(E)=number of outcomes favourable to Enumber of all possible outcomesP(E)=\frac{\text{number of outcomes favourable to }E}{\text{number of all possible outcomes}}.
Q2

Find the probability of getting a head when a fair coin is tossed once.

A fair coin has two equally likely outcomes: H and T. Favourable outcome for head is 1. So P(H)=12P(H)=\frac12.
Q3

A fair die is thrown once. Find the probability of getting an even number.

Outcomes are 1,2,3,4,5,61,2,3,4,5,6. Even outcomes are 2,4,62,4,6, so probability =36=12=\frac36=\frac12.
Q4

What are the minimum and maximum possible values of probability?

For any event EE, 0P(E)10\le P(E)\le1. Impossible event has probability 00 and sure event has probability 11.
Q5

State and use the complement rule. If P(E)=35P(E)=\frac35, find P(not E)P(\text{not }E).

The complement rule is P(E)+P(E)=1P(E)+P(\overline E)=1. So P(E)=135=25P(\overline E)=1-\frac35=\frac25.
Q6

A card is drawn from a well-shuffled deck of 52 cards. Find the probability of getting a king.

There are 4 kings in a deck of 52 cards. Probability =452=113=\frac4{52}=\frac1{13}.