Question

one is asked to say a two digit number. what is the probability.
a. Both digits being different
b. The first digit being larger
c. The first digit being smaller. ​

Answer 1

There are 90 two digit numbers(99–9). Out of this there are 6 numbers divisible by 15(15, 30, 45, 60, 75, 90), which are also divisible by 5. Therefore, the favorable cases are 30–6=24. Hence, the required probability is 24/90 = 4/15.

Answer 2

a) 81/90=8/9
b)41/90
c)40/90