Question

A CI is desired for the true average stray-load loss μ (watts) for a certain type of induction motor when the line current is held at 10 amps for a speed of 1500 rpm. Assume that stray-load loss is normally distributed with σ = 2.6. (Round your answers to two decimal places.)

(a) Compute a 95% CI for μ when n = 25 and x = 56.2.

(_____,______) watts

(b) Compute a 95% CI for μ when n = 100 and x = 56.2.
(_____,______) watts
(c) Compute a 99% CI for μ when n = 100 and x = 56.2

(_____,______) watts.

(d) Compute an 82% CI for μ when n = 100 and x = 56.2.

(_____,______) watts

(e) How large must n be if the width of the 99% interval for μ is to be 1.0? (Round your answer up to the nearest whole number
n = _____

Answer 1

a) At 95% confidence level, the critical value is z0.025 = 1.96

The 95% confidence interval is

b) The 95% confidence interval is

c) At 99% confidence level, the critical value is z0.005 = 2.58

The 99% confidence interval is

d) At 82% confidence level, the critical value is z0.09 = 1.34

The 82% confidence interval is

e) Margin of error = 1/2