Question

A variable x is normally distributed with unknown mean and standard deviation =2. if the probability that x exceeds 7.5 is 0.8023, find the mean

Answer 1

@ganeshie8

Answer 2

im getting 9.2 am i correct??

Answer 3

My statistics is a bit rusty but I think the mean will not be greater than 7.5.

z = (X - μ) / σ

z = (7.5 - μ) / 2

The z score paired with .8023 is .805 which is above the mean.

.805 = (7.5 - μ) / 2

μ = 5.89

Here's a link to the area under the curve chart:

https://figures.boundless.com/18108/large/normal01.jpe