JEE Advanced 2013 · Paper 1 · Mathematics Q42

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MathematicsSingle correct+2Question 42 of 60

Four persons independently solve a certain problem correctly with probabilities $\frac12,\frac34,\frac14,\frac18$ . Then the probability that the problem is solved correctly by at least one of them is

\dfrac{235}{256}

\dfrac{21}{256}

\dfrac3{256}

\dfrac{253}{256}

Answer and worked solution

Official answer: A

Complement. Nobody solves it with probability $\frac12\cdot\frac14\cdot\frac34\cdot\frac78=\frac{21}{256}$ .

At least one: $1-\frac{21}{256}=\frac{235}{256}$ .

(A)

Topics:Independent events

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JEE Advanced 2013 · Paper 1, Mathematics question 42