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 = 2.8. (Round your answers to two decimal places.)

(a) Compute a 95% CI for μ when n = 25 and x = 52.5.

...........................Watts?

(b) Compute a 95% CI for μ when n = 100 and x = 52.5.

.............................Watts?

(c) Compute a 99% CI for μ when n = 100 and x = 52.5.

.............................Watts?

(d) Compute an 82% CI for μ when n = 100 and x = 52.5.

..............................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 =

You may need to use the appropriate table in the Appendix of Tables to answer this question.

Answer 1

Part a)

Confidence Interval :-



Lower Limit =
Lower Limit = 51.4024
Upper Limit =
Upper Limit = 53.5976
95% Confidence interval is ( 51.40 , 53.60 )

Part b)

Confidence Interval :-



Lower Limit =
Lower Limit = 51.9512
Upper Limit =
Upper Limit = 53.0488
95% Confidence interval is ( 51.95 , 53.05 )

Part c)

Confidence Interval :-



Lower Limit =
Lower Limit = 51.7788
Upper Limit =
Upper Limit = 53.2212
99% Confidence interval is ( 51.78 , 53.22 )

Part d)

Confidence Interval :-



Lower Limit =
Lower Limit = 52.1246
Upper Limit =
Upper Limit = 52.8754
82% Confidence interval is ( 52.12 , 52.88 )

Part e)

Sample size can be calculated by below formula



n = 209
Required sample size at 99% confident is 209