Question

9. An envi ronmental scientist is catching fish from the Great Lakes and testing them for the presence of an invasive parasite. After a sample analysis that included 175 rounds of testing, the scientist finds that the sample mean infection rate, is 7.07 fish per round. , is 54.37 fish per round and the sample standard deviation, a. Construct a 95% confidence interval for the mean infection rate in the total fish population. b. Explain how your work in part would have been different if the sample size had been only Explain what this figure means. 12 rounds of testing instead of 175. 10. )Up to 20% of people in the United States will catch the flu this year. Use this figure as the population mean, and assume you work in an office space with 30 coworkers: a. How many of your coworkers would you expect to get the flu this year? b. What's the standard deviation? c. Using the appropriate approximation, determine P(x>1), that is, the probability that more than one of your coworkers will get the flu this year.

Answer 1

9. Here

sample mean

sample standard deviation

s = 7,07

and sample size

n 175

a) a 95% confidence interval for the mean infection rate in total fish population

7.07 7.07 = (5437 +10.025. 174:54.3T+ ー*to to.025,174)

(54.37-7.07 V175 * 1.97369. 54.37 7.07 * 1.97369) 175

(53.3152, 55.4248)

b) Width of the confidence interval

i.e. width of the confidence interval is proportional to

So, if sample size decreases, the width of the confidence interval increases.