SOLUTION: Hi tutors, can you help me answer this question? thanks A jar contains red, blue, yellow, pink and white jelly beans. James wants to estimate the number of jelly beans in the jar.

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Question 981511: Hi tutors, can you help me answer this question? thanks
A jar contains red, blue, yellow, pink and white jelly beans. James wants to estimate the number of jelly beans in the jar.
James adds 90 black jelly beans and mixes the jelly beans thoroughly. He draws out 120 jelly beans at random and finds that he has 18 black jelly beans. How many jelly beans should he estimate were originally in the jar?
A. 480
B. 510
C. 600
D. 690
Answer by josgarithmetic(39617) (Show Source):
You can put this solution on YOUR website!
n jelly beans, none black, originally in the jar.

Added 90 black beans and mixed;
removed 120 beans and counted 18 black beans.

Concentration of black jelly beans is near .

Quantity of jelly beans after the addition and mixing became n+90.

If this equation makes sense, then all needs to be done now is solve for n.
The focus in this proportion equation is the comparison of concentrations of
the black jelly beans.