RS Aggarwal Class 7 Math Twenty-Three Chapter Probability Exercise 23 Solution

EXERCISE 23

(1) A coin is tossed 300 times and we get

Head: 136 times and tail: 164 times.

When a coin is tossed at random, what is the probability of getting (i) a head, (ii) a tail?

Solution: Total number of tossed = 300.

Number of heads = 136

Number of tails = 164

(i) P (getting a head) = 136/300 = 34/75

(ii) P (getting a tail) = 164/300 = 41/75

(2) Two coins are tossed simultaneously 200 times and we get

Two heads: 58 times; one head: 83 times; 0 head: 59 times.

When two coins are tossed at random, what is the probability of getting (i) 2 heads, (ii) 1 head, (ii) 0 head?

Solution: Probability of getting 1 head = 83/200 = 0.415

Probability of getting 0 heads = 59/200 = 0.295

Number of two heads = 83 + 59 = 142

= 200 – 142 = 58

Probability of getting 2 heads = 58/200 = 0.29

(3) A dice is thrown 100 times and the outcomes are noted as given below:

Outcome	1	2	3	4	5	6
Frequency	21	14	18	15	23	9

When a dice is thrown at random, what is the probability of getting a (i) 3, (ii) 6, (iii) 4, (iv) 1?

Solution: Total number of trials = 100.

(i) P (getting a 3) = 18/100 = 9/50

(ii) P (getting a 6) = 9/100

(iii) P (getting a 4) = 15/100 = 3/20

(iv) P (getting a 1) = 21/100

(4) In a survey of 100 ladies it was found that 36 like coffee while 64 dislike it.

Out of these ladies, one is chosen at random. What is the probability that the chosen lady (i) likes coffee, (ii) dislike coffee?

Solution: Total number of ladies = 100.

Number of ladies who like coffee = 36.

Number of ladies who dislike coffee = 64.

(i) P (chosen lady likes coffee) = 36/100 = 9/25

(ii) P (chosen lady dislikes coffee) = 64/100 = 16/25.