Stat
posted by MK on .
Kindergarten children have heights that are approximately distributed normal. A random sample of size 20 is taken and the mean x and the standard deviation s are calculated ( x = 40 inches and s = 3).
a. Is there sufficient evidence to indicate that the mean of kindergarten children’ height exceeds 40 inches? Perform a test
using alpha=.05.
b. What is the probability that the mean of kindergarten children’ heights would be between 39 and 42.5 inches?

a. In a normal distribution, 50% are above the mean. For confidence interval,
95% = mean ± 1.96 SEm
b. Z = (scoremean)/SEm
SEm = SD/√n
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability between the two Z scores.