Question

Two students each use a random number generator to pick an integer between 9 and 15 inclusive. What is the probability that they pick the same number? (Enter your answer as a fraction.)

Answer 1

The first Student can have any integer between 9 and 15 inclusive .

That gives him 7 possible integers out of 7 integers

Probability of the first student having the "right" integer = 7 / 7 = 1

Now,

Second person has to pick that particular integer picked up by first student.

There are in total 7 integer between 9 and 15 inclusive.

So, Probability of picking a particular integer = 1 / 7

To find the probability that both student pick same integer, we have to multiply their separate probabilities.

Hence,

Probability that two students pick the same number =