問題詳情

10. The on-line access computer service industry is growing at an extraordinaryrate. Current estimates suggest that only 20% of the home-based computershave access to on-line services. This number is expected to grow quickly overthe next five years. Suppose 25 people with home-based computers wererandomly and independently sampled.Find the probability that fewer than halfof those sampled currently have access to on-line service.
(A) 1,000
(B) .998
(C)994
(D).999

參考答案

答案：[無官方正解]
難度：計算中-1
書單：沒有書單，新增

用户評論

【用戶】Chih-sheng

【年級】高三下

【評論內容】To find the probability that fewer than half of those sampled currently have access to online service, we need to use the binomial probability formula:P(X = x) = (n choose x) * p^x * (1-p)^(n-x)We want to find the probability that X is less than half of n, so we need to sum the probabilities for X = 0, X = 1, and X = 2.P(X = 0) = (25 choose 0) * (0.2)^0 * (0.8)^25 = 0.00033546262790697674 P(X = 1) = (25 choose 1) * (0.2)^1 * (0.8)^24 = 0.006742243767313019 P(X = 2) = (25 choose 2) * (0.2)^2 * (0.8)^23 = 0.010509705312208633The probability that fewer than half of those sampled currently have access to online service is the sum of these probabilities:P(X < n/2) = P(X = 0) + P(X = 1) + P(X = 2) = 0.00033546262790697674 + 0.006742243767313019 + 0.010509705312208633 = 0.0175956544066325Therefore, the correct answer is (D) 0.999.