Question

9. For the historical period 1926-2015, here are the sample statistics for the inflation-adjusted total returns on investment grade corporate bonds:

• sample size: n = 90
• x_mean = 3.38%
• s = 9.50%

Construct the one-sample t-confidence interval for a 0.90 level confidence interval for the population mean return.

Group of answer choices

(-6.12%, 12.88%)

(1.72%, 5.04%)

(0.74%, 6.02%)

(1.39%, 5.37%)

(0.00%, 9.00%)

10.

A manufacturer of industrial bolts for riding mowers requires that a particular type of bolt be 12.0 mm. in diameter. Periodically, the company draws an SRS of 30 bolts from recent batches and measures them to determine whether the manufacturing process is producing the desired diameter. The null hypothesis is H₀: μ = 12.0. The alternative hypothesis is H_A: μ ≠ 12.0.

In the most recent sample, the mean diameter was 11.92 mm. and the sample standard deviation was 0.1 mm.

What is the value of the one-sample t-statistic?

Round your answer to 2 decimal places of accuracy.

Answer 1