Question

g You measure 40 textbooks' weights, and find they have a mean weight of 73 ounces. Assume the population standard deviation is 11.7 ounces. Based on this, construct a 99% confidence interval for the true population mean textbook weight.

Answer 1

The confidence interval is 73 ± 4.8

Explanation:

Here, we want to construct a 99% confidence interval

Mathematically;

mean ± Z * S.D/√n

From the question

mean = 73

SD = 11.7 ounces

Z score = 2.576 for 99% Confidence interval

n = sample size = 40

Thus;

73 ± (2.576 * 11.7)/√40

73 ± 4.8

So the range of values are;

73 + 4.8 and 73-4.8

= 77.8 and 68.2

The lower boundary is 68.2

The upper boundary is 77.8