WAEC 2016 · Paper 2 · Q5

Probability & distributions

The probabilities that Ago, Sulley and Musa will gain admission to a certain university are $\frac45$ , $\frac34$ and $\frac23$ respectively. Find the probability that:

(a)
none of them will gain admission;
(b)
only Ago and Sulley will gain admission.

Worked solution (try it first)

The chances of not gaining admission are $\frac15$ , $\frac14$ and $\frac13$ .

(a)

None: $\frac15 \times \frac14 \times \frac13 = \frac{1}{60}$ .

(b)

Only Ago and Sulley: they succeed and Musa fails: $\frac45 \times \frac34 \times \frac13 = \frac{1}{5}$ .

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