waecmaths question:
A box contains 2 white and 3 blue identical balls. If two balls are picked at random from the box, one after the other with replacement, what is the probability that they are of different colors?
Option A:
$\frac{2}{3}$
Option B:
$\frac{3}{5}$
Option C:
$\frac{7}{20}$
Option D:
$\frac{12}{25}$
waecmaths solution:
$\Pr (WB)+\Pr (BW)=\left( \frac{2}{5}\times \frac{3}{5} \right)+\left( \frac{3}{5}\times \frac{2}{5} \right)=\frac{6}{25}+\frac{6}{25}=\frac{12}{25}$
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