a is chosen from the set {1,2,3,4,5}, and b is chosen from the set {5,6,7,8,9}. What is the probability that the product ab is a prime number?

Guest Feb 11, 2021

#1**0 **

*a is chosen from the set {1,2,3,4,5}, and b is chosen from the set {5,6,7,8,9}. What is the probability that the product ab is a prime number?*

There can be 5 x 5 products. 25 possible

For the product to be a prime numer,

**a** must be 1 and **b** must be either 5 or 7. 2 possible

Probability of the product being a prime is **2 / 25**.

Guest Feb 11, 2021