# A bag contains 4 white balls and some red balls. If the probability of drawing a white ball from the bag is 2/5, find the number of red balls in the bag.

Dear student

let the number of the red ball be x.
the total number of balls = 6+x.
the probability of drawing a white ball is 2/5.
therefore:
$\frac{6}{6+x}=\frac{2}{5}\phantom{\rule{0ex}{0ex}}2\left(6+x\right)=6*5\phantom{\rule{0ex}{0ex}}6+x=3*5=15\phantom{\rule{0ex}{0ex}}x=15-6\phantom{\rule{0ex}{0ex}}x=9$

thus the number of red balls is 9

Regards

hope this helps you.

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