Two distinct numbers are chosen from 1,   3 ,     5,   7 . . . . . . . . 151,   153,   155 and multiplied. The probability that the product is a multiple of 5 is

Step-by-step solution

Given numbers 1,   3 ,   5 . . . . . . . . ,   153,   155 T n = a + n - 1 d ⇒ 155 = 1 + n - 1 2 ⇒ n = 7 8 Total number of ways = 78 C 2 = 3003 The numbers which are multiple of 5 are 5,   15,   25 ,   . . . . ,   155 155 = 5 + n - 1 10 ⇒ n = 1 6 The number of ways in which product is a multiple of 5 = (Both two numbers from 5,15,25 , . . . . . . , 155 ) or (one number from 5,15,25 , . . . . . . , 145 and one number from the remaining numbers). = 16 C 2 + 16