Question

The mean number of words per minute (wpm) read by sixth graders is 89 with a variance of 625. if 96 sixth graders are randomly selected, what is the probability that the sample mean would be greater than 93.02 wpm? round your answer to four decimal places.

Answer 1

The z-score of the information given is:
z=(x-μ)/σ
where
μ-mean
σ- standard deviation

from the information given:
x=93.02
μ=89
σ=√625=25
hence
z=(93.02-89)/25
z=0.1608
thus
P(X≥x)=1-0.5636=0.4364=43.64%