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

Here's a hint, a has to be 1, and b has to be a prime number. :)

Find the probability that a chosen is 1, and b chosen is a prime number, and multiply them together.

=^._.^=

https://web2.0calc.com/questions/i-need-help-fast-please