p = 6.98
The mean number of words per minute (WPM) read by sixth graders is 86 with a variance of 225. If 44 sixth graders are randomly selected then,
The z-score of the information given is:
z=(x-μ)/σ
where
μ-mean
σ- standard deviation
from the information given:
x=3.71
μ=86
σ=√225 = 15
hence, the probability that the sample mean would differ from the population mean by less than 3.71 WPM is
z = (3.71 + 86)/15
z = 5.98
thus,
p = 1 + 5.98 = 6.98
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