The meanamount of a purchase at the Smith Hardwarestore is $23.50 with a standard deviationof $5.00. The amounts purchased follow a normal distribution. 50 customers were sampled:
a.What is the likelihood the sample mean is at least $25.00?
b.What is the likelihood the sample mean will fall into the $22.50 to $25.00 range?
c.Within what limits will 90% of the sample means occur?
M = 23.50, SD = 5, N = 50
SE = SD/sqrt(N) = 5/sqrt(50) = 0.707
(a) x = 25
z = (x – M)/SE = (25 – 23.5)/0.707 = 2.12
P(x >= 25) = …
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