A group of biologists wish to study the life span of the common housefly.They want to estimate the mean life span with 80% confidence and a width on the interval of estimation no greater than 1 hr.How many samples should they draw if a previous study indicates that the standard deviation of life span is 2.43 hr?
A) 10
B) 39
C) 230
D) 9

Question

Quizplus · Accepted Answer

To estimate the sample size, we use the formula: n = (Z^2 * σ^2) / (E^2), where Z is the z-score corresponding to the desired confidence level (80% = 1.28), σ is the population standard deviation, and E is the desired width of the interval. Plugging in the values, we get: n = (1.28^2 * 2.43^2) / (1^2) = 38.9, which we round up to 39. Therefore, the biologists should draw a sample of 39 houseflies to estimate the mean life span with 80% confidence and a width no greater than 1 hour.

A Group of Biologists Wish to Study the Life Span