A crossword puzzle is published in ‘The Times’ each day of the week, except Sunday. A man can comple

Question

A crossword puzzle is published in ‘The Times’ each day of the week, except Sunday. A man can complete, on average, $8$ out of $10$ of the crossword puzzles. Find the expected value and the standard deviation of the number of completed crosswords in a given week. Find the probability that he will complete at least $5$ in a given week. Given that he completes the puzzle on Monday, find the probability that he will complete at least $4$ in the rest of the week. Find the probability that, in a period of four weeks, he completes $4$ or less in only one of the four weeks.

Accepted Answer

(a) $4.8, 0.980$; (b) $0.655$; (c) $0.737$; (d) $0.388$.

Number of successful attempts of crossword puzzles

Number of successful attempts of crossword puzzles