Question # 2

Researchers studying infant head circumferences (in centimeters) wish to test if the mean head circumference differs from the historical mean of 34.5 cm. The researchers obtain a sample of 15 infants with a mean head circumference of 34.86 cm and a standard deviation of 0.58 cm.

At the α = 0.05 significance level, test the claim

HO: µ = 34.5

HA: µ ≠ 34.5

a) Is this an upper tail, lower tail, or two-tail test? (5 points)

.

b) Are we testing means or proportions? (5 points)

c) State the rule of rejection (in terms of p-value and level of significance) (5 points)

Z test with a a= 0.05 and the decision rule is that if

we reject H0 if 0.05 > p-value .

d) Find the p-value (5 points)

e) Should you reject or not reject HO? (5 points)

f) Does the result suggest that the mean head circumference differs from 34.5 cm? (5 points)