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The probability that A hits a target is 15\frac{1}{5} and the probability that B hits it is 23\frac{2}{3}. The probability that the target will be hit if both A and B shoot at it independently is:

Solution

✅ Correct Option: 1

We need to find the probability that the target is hit, meaning at least one of A or B hits it.

P(A hits)=15P(A \text{ hits}) = \dfrac{1}{5}

P(B hits)=23P(B \text{ hits}) = \dfrac{2}{3}

Instead of calculating each case separately (only A hits, only B hits, both hit), we use a faster approach:

P(at least one hits)=1−P(nobody hits)P(\text{at least one hits}) = 1 - P(\text{nobody hits})


P(A misses)=1−15=45P(A \text{ misses}) = 1 - \dfrac{1}{5} = \dfrac{4}{5}

P(B misses)=1−23=13P(B \text{ misses}) = 1 - \dfrac{2}{3} = \dfrac{1}{3}


Since A and B shoot independently, we can multiply their miss probabilities to get the probability that both miss:

P(both miss)=45×13=415P(\text{both miss}) = \dfrac{4}{5} \times \dfrac{1}{3} = \dfrac{4}{15}


Using the complement:

P(target is hit)=1−415=15−415=1115P(\text{target is hit}) = 1 - \dfrac{4}{15} = \dfrac{15 - 4}{15} = \boxed{\dfrac{11}{15}}

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