Question

A bag contains 4 red marbles, 5 blue marbles, 6 yellow marbles, and 7 green marbles; Jonathan randomly grabs one marble, puts it back then draws a second marble. What is the probability that the first marble was red, and the second marble was green?

Answer 1

p ( first marble red ) = 4/22

p ( second marble green ) = 7/22

Since total number of marbles r 22, then the denominator is 22 also. When Jonathan puts back the red marble aft the first round, this means with replacement so there's no change in denominator for the second round.