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A box contains 40 identical balls of which 10 are red and 12 are blue. if...

Mathematics
WAEC 2021

A box contains 40 identical balls of which 10 are red and 12 are blue. if a ball is selected at random from the box what is the probability that it is neither red nor blue?

  • A. \(\frac{9}{20}\)
  • B. \(\frac{3}{10}\)
  • C. \(\frac{1}{4}\)
  • D. \(\frac{11}{20}\)
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Correct Answer: Option A
Explanation

Total number = 40

number of red = 10

Pr (R) = \(\frac{10}{40}\)


Pr(blue) = \(\frac{12}{40}\)

probability (neither red nor blue)
= 1 - \(\frac{10}{40}\) -  \(\frac{12}{40}\)
= \(\frac{40 -12 -10}{40}\)
= \(\frac{18}{40}\) or  \(\frac{9}{20}\)


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