The cookie Jar
A jar of cookies contains
regular
oreo cookies and
golden
oreo cookies.
If a single cookie is selected at random from the jar, the probability that it is
golden
is
.
If 2 cookies are selected from the jar, the probability that they are both
golden
is
.
What is the total number of cookies in the jar?
The answer is 27.
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1 solution
Let N be the total number of cookies.
Let G be the number of golden oreo cookies.
P(a single golden oreo)=G/N=1/3 (1)
P( 2 golden oreo cookies)=(G/N)x((G-1)/(N-1))=4/39 (2)
From (1) G=N/3
From (2) (1/3)x((N/3 - 1)/(N - 1))=4/39
N=27