150 air conditioners were tested and it was found that the average power usage per hour...

150 air conditioners were tested and it was found that the average power usage per hour during the summer months (for around 9 hours per day) is 3800 W. Find the 90% confidence interval if sigma = 80 W.

Expert Solution

We need to construct a 90% confidence interval for the average power usage per hour during the summer months.,that is for population mean . Since 90%, =0.10.

Given sample mean, and population standard deviation, and sample size, n=150.

Since population standard deviation is known, we use z for calculating the critical value.

For =0.10, critical value, .(From Standared normal table).

The lower and upper limits of the 90% confidence interval is,

Therefore, the 90% confidence interval for the for the average power usage per hour during the summer months.,that is for population mean is (3789.256,3810.744).

That is we can be 90% confident that the average power usage per hour during the summer months lies between (3789.256,3810.744).

orchestra answered 2 years ago

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