Question

Construct a 90​% confidence interval for the population mean μ.

n=12

mean = 4263.1

s/d = 260

Answer 1

Given that, sample size (n) = 12

sample mean = 4263.1 and

sample standard deviation (s) = 260

Degrees of freedom = 12 - 1 = 11

t-critical value at significance level of 0.10 with 11 degrees of freedom is,

Excel Command : =TINV(0.10, 11) = 1.796

The 90% confidence interval for the population mean μ is,

Therefore, required 90% confidence interval is (4128.3003, 4397.8997)