I have a bag of tiles 0-9. Without looking select a tile, record, return tile, select a second tile. What is the probability that exactly one tile will be a prime number?

Answer 1

You will have 2 choices
PN -- N for not prime
NP

prob = (4/9)(5/9) + (5/9)(4/9) = 40/81

Answer 2

looks like I forgot how to count, there are 10 tiles not 9

so
prob = (4/10)(6/10) + (6/10)(4/10) = 48/100 = 12/25