Probability — Chapter Test | Class 10 IMO

Q1

A card is drawn from 52 cards. The probability that it is an ace is:

4 aces out of 52 give 1/13.

Q2

The probability of an impossible event is:

An impossible event never happens, so its probability is 0.

Q3

A piggy bank has 20 one-rupee, 10 two-rupee and 5 five-rupee coins. The probability that a coin tipped out is a five-rupee coin is:

5 five-rupee coins out of 35 give 5/35 = 1/7.

Q4

Out of 12 pens, 3 are defective. The probability that a pen picked at random is good is:

9 good pens out of 12 give 9/12 = 3/4.

Q5

200 light bulbs include 6 defective ones. The probability that a randomly chosen bulb is defective is:

6/200 = 3/100.

Q6

Outcomes are called equally likely when they have:

Equally likely outcomes each have the same probability.

Q7

Two dice are thrown. The probability that the sum is 12 is:

Only (6, 6) gives a sum of 12, so 1/36.

Q8

Two coins are tossed together. The probability of getting at least one head is:

All outcomes except TT are favourable: 3/4.

Q9

A standard deck contains how many cards?

A standard deck has 52 cards.

Q10

Two fair coins are tossed together. The probability of getting two heads is:

Only HH out of {HH, HT, TH, TT} is favourable, so 1/4.

Q11

The sum of the probabilities of all elementary outcomes of an experiment is:

All outcome probabilities together total 1.

Q12

The probability that an ordinary (non-leap) year has 53 Mondays is:

An ordinary year has 1 extra day, which is a Monday in 1 of 7 cases, so 1/7.

Q13

The probability of an event can never be:

Probabilities lie in [0, 1], so they cannot exceed 1.

Q14

Two dice are thrown. The probability that the sum of the numbers is 7 is:

Six pairs give a sum of 7 out of 36 outcomes, so 6/36 = 1/6.

Q15

The probability that a leap year chosen at random contains 53 Sundays is:

A leap year has 52 weeks plus 2 extra days; 2 of the 7 pairs include a Sunday, so 2/7.