You measure 27 textbooks' weights, and find they have a mean
weight of 70 grams. Assume the population standard deviation is 5.4
grams. Based on this, construct a 94% confidence interval for the
true population mean textbook weight. Assume n is too small to
allow use of the normal. Instead use a t statistic.
What is the degrees of freedom?
dof =
What is the confidence interval. Give your answers as decimals,
to two places
< μμ <
df = n - 1 = 27 - 1 = 26
Confidence Interval
X̅ ± t(α/2, n-1) S/√(n)
t(α/2, n-1) = t(0.06 /2, 27- 1 ) = 1.967
70 ± 1.967 * 5.4/√(27)
Lower Limit = 70 - 1.967 * 5.4/√(27)
Lower Limit = 67.96
Upper Limit = 70 + 1.967 * 5.4/√(27)
Upper Limit = 72.04
67.96 < < 72.04
You measure 27 textbooks' weights, and find they have a mean weight of 70 grams. Assume...
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