Question

The trout in a lake have historically had an average weight of 11.2 pounds. It is suspected that pollution from a nearby factory has affected the weight of trout in recent years.

Suppose you take a random sample of 50 trout from the lake, and you find that the sample mean of their weight is 10.2 pounds, with a sample standard deviation of 2.1 pounds.

(a) The standard error of the (sample) mean is ­­­­­___________________________

(b) Find a 95% confidence interval for the population mean trout weight is (_______, ________)

(c) Your confidence interval in (b) provides evidence to determine if (i) the mean weight might still be 11.2 pounds, or if (ii) the mean appears to have changed, at the significance level is 0.05. Which of these two alternatives does the confidence interval support?

Explain your answer.

Answer 1

Confidence Interval



Lower Limit =
Lower Limit = 9.6032
Upper Limit =
Upper Limit = 10.7968
95% Confidence interval is ( 9.6032 , 10.7968 )

Margin of Error =

Standard Error =

95% Confidence interval is ( 9.6032 , 10.7968 )

Since does not lies in the interval

ii) The mean appears to have changed, at the significance level is 0.05.