Question

20 cards numbered 1,2,3,.....20 are put in a box. One boy draws a card from the box. Find the probability that the number on the card is. A. Prime. B. Divisible by 3. C. Divisible by 5 *

Answer 1

Answer:

A) prime no =2, 4,6,8,10,12,14,16,18,20

( the probability of getting a prime no) =10/20

=1/2

B) divisible by 3=3, 6,9,12,15,18

(probability of getting divisible by 3) =6/20

3/10

C) divisible by 5= 5,10,15,20

(probability of getting divisible by 5) =4/20

1/5

Answer 2

Answer:

answer a is 2/5

answer b is 3/10

answer c is 1/5

Step-by-step explanation:

explanation of a is :

prime no. from 1 to 20 are 2,3,5,7,11,13,17,19.

so we have total prime no. is 8

now the formula for probability is favourable outcomes/total outcomes,so

P(x) = 8/20 = 2/5.

explanation of b is :

the no. which are divisible by 3 from 1 to 20 are 3,6,9,12,15,18.

so we have total no.is 6 that are divisible by 3 from 1 to 20

by the upper formula

we have P(x) =6/20 = 3/10.

explanation of c is :

the no. from 1 to 20 that are divisible by 5 are 5,10,15,20

so the total no are 4 that are divisible by 5 from 1 to 20

P(x) = 4/20 = 1/5