JAMB - Mathematics (2018 - No. 12)

The probabilities that John and James pass an examination are \(\frac {3}{4}\)and \(\frac {3}{5}\) respectively. Find the probability of both boys failing the examination.

 

\(\frac {1}{10}\)
\(\frac {2}{10}\)
\(\frac {9}{20}\)
\(\frac {11}{20}\)

Explanation

To find the probability of both John and James failing the examination:

Probabilities of failing:
 \(P(\text{John fails}) = 1 - P(\text{John passes}) = 1 - \frac{3}{4} = \frac{1}{4}\)
 \(P(\text{James fails}) = 1 - P(\text{James passes}) = 1 - \frac{3}{5} = \frac{2}{5}\)

Probability of both failing:
 \(P(\text{Both fail}) = P(\text{John fails}) \times P(\text{James fails}) = \frac{1}{4} \times \frac{2}{5} = \frac{2}{20} = \frac{1}{10}\)

Thus, the probability of both boys failing the examination is:
\(\frac{1}{10}\)

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