Question

A bag of marbles contains six red marbles, four blue marbles, eight green marbles, and two yellow marbles. marble is selected at random from the bag and not replaced and then anoter marble is selected. What is the probability that both marbles selected in this situation are described as yellow?

a)1/190
b)1/100
c)2/190
d)1/10

Answer 1

okay, so u have 6R, 4B, 8G, 2Y marbles.....so in all, u have 20 marbles.
probability of selecting one yellow marble from these 20 marbles is
\[\frac{C _{1}^{2}} {C _{1}^{20} }\]
so now u have only 1Y and in all, 19 marbles remaining.
the probability of again getting a yellow marble from the remaining 19 marbles is
\[\frac{C _{1}^{1}} {C _{1}^{19}}\]
just multiply these two and u'll have ur answer.