Question

One jar holds 16 red marbles and 4 blue marbles. A second jar holds 75 white marbles and 25 blue marbles. What is the probability that a blue marble will be drawn from both jars?

Answer 1

Jar 1 : 16 red, 4 blue....total = 20
P(blue) = 4/20 reduces to 1/5

jar 2 : 75 white,25 blue...total = 100
P(blue) = 25/100 reduces to 1/4

P(blue,blue) = 1/5 * 1/4 = 1/20 or 0.05 or 5%

Answer 2

$|\Omega|=20\cdot100=2000\\ |A|=4\cdot25=100\\\\ P(A)=\dfrac{100}{2000}=\dfrac{1}{20}$