Question

Four persons independently solve a certain problem correctly with probabilities $\frac{1}{2},\frac{3}{4},\frac{1}{4},\frac{1}{8}$.Then the probability that the problem is solved correctly by at least one of them is

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

P (at least one of them solves correctly) = 1 – P (none of them solves correctly)
$=1-(\frac{1}{2}\times \frac{1}{4}\times \frac{3}{4}\times \frac{7}{8})=\frac{235}{256}$ ​