If the total weight of the 9 wrestlers exceeds 5000 pounds, then the mean weight "\\bar{x}" of the 9 wrestlers must exceed "5000\/9" pounds.
Change the criterion for failing to operate from "total weight exceeding 5000 pounds" to "mean weight for 9 people exceeding "5000\/9" pounds".
Let "X=" the mean weight in pounds: "X\\sim N(\\mu,\\sigma^2)"
Then
Given that "\\mu=540" pounds, "\\sigma=45\/\\sqrt{9}" pounds.
"=1-P(Z\\leq{{5000 \\over 9}-540 \\over 15})\\approx1-0.850141\\approx0.1499"
The probability that the elevator will fail to operate is "0.1499."
Comments
Leave a comment