SOLUTION: A bag contains 16 red balls and 20 blue balls only. How many white balls must be added to the bag so that the probability of randomly picking a red ball is equal to 2/5?

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Question 857455: A bag contains 16 red balls and 20 blue balls only. How many white balls must be added to the bag so that the probability of randomly picking a red ball is equal to 2/5?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

Let x represent the number of white balls added    

Total of (36 + x) balls: 16 red, 20 blue and x white

P(red ball) = 16%2F%2836%2Bx%29+=+2%2F5 | Cross Multiplying to solve

                  80 = 72 + 2x

                   8 = 2x

                   x = 4, the number of white balls added

CHECKING our answer***

  16/40 = 2/5

Wish You the Best in your Studies.