In a jar there are balls in different colors: Blue, Red,

Question

In a jar there are balls in different colors: Blue, Red, Green, and Yellow
The probability of drawing a blue ball is 1/8
The probability of drawing a red ball is 1/5
The probability of drawing a green ball is 1/10. If a jar cannot contain more than 50 balls, how many yellow balls are in the jar?

A. 23
B. 20
C. 24
D. 17
E. 25

sidbidus · Answer

A 23 

B/T = 1/8
R/T = 1/5
G/T = 1/10

LCM of 8,5,10 i.e not more than 50 is 40

So total balls = 40
B = 5
R = 8
G = 4
Y = 23

LM · Answer

P(B)=1/8

P(R)=1/5

P(G)=1/10

P(Y)=1/x ( assumption )

P(B) = N(B)/ Total =1/8 ( N(B) is the number of blue balls )

P(R) = N(R)/ Total =1/5 ( N(R) is the number of blue balls )

P(G) = N(G)/ Total =1/10 ( N(G) is the number of blue balls )

P(Y) = N(Y)/ Total =1/x ( N(Y) is the number of blue balls )

From all the above equations we have:

Total = 8N(B) = 5N(R) = 10N(Y)

Clearly this is possible if and only if N(B) =5, N(R) = 8, N(Y) = 4

and total will be 40. ( which is of course less than 50 as mentioned in the question )

Thus N(Y) = 40-(5+8+4) = 23
=============== :wink:

ontheway · Answer

dumb on my side

got the point

Thanks guys.

GMATBLACKBELT · Answer

1 - (1/8+1/5+1/10) ---> 1 - 17/40 ---> 23/40.

Since the balls must be less than 50. denom cannot be greater than 40.

so 23 is the number of yellow balls.

A.

In a jar there are balls in different colors: Blue, Red,

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