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Nov 2018 p62 q3
3013
Jake attempts the crossword puzzle in his daily newspaper every day. The probability that he will complete the puzzle on any given day is 0.75, independently of all other days.
Find the probability that he will complete the puzzle at least three times over a period of five days.
Solution
Let the random variable \(X\) represent the number of days Jake completes the puzzle in 5 days. \(X\) follows a binomial distribution with parameters \(n = 5\) and \(p = 0.75\).
We need to find \(P(X \geq 3)\), which is \(P(X = 3) + P(X = 4) + P(X = 5)\).
Using the binomial probability formula \(P(X = k) = \binom{n}{k} p^k (1-p)^{n-k}\):