Question

There are 100 tickets in a box numbered 00, 01, ...... 99. One ticket is drawn at random. If A is the event that sum of the digits of the number is 7 and B is the event that product of digit is 0. Then P(A/B) = ______

(a) (2/13)

(b) (2/19)

(c) (1/50)

(d) None   

Answer 1

The correct option (b) (2/19)  

Explanation:

U = {00, 01,...... 99}

A = sum of digit = 7

∴ A = {07, 16, 25, 34, 43, 52, 61, 70} 

B = product is 0 

∴ B = {00, 01 ...... to 09, 10, 20 ........ 90} and n(B) = 19

∴ (A ∩ B) = {07, 70}

P(A/B) = [{n(A ∩ B)}/{n(B)}] = (2/19).