Answer:
The manager should use a sample size of 12 to determine the average travel expenditure
Step-by-step explanation:
Spent about 20 cents per mile. Distance of 15 miles
We have the mean per a distance, so we use the Poisson distribution. In this distribution, the standard deviation is the square root of the mean. So
Confidence interval:
We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of .
That is z with a pvalue of , so Z = 1.96.
Now, find the margin of error M as such
In which is the standard deviation of the population and n is the size of the sample.
What sample size should the manger use to determine the average travel expenditure?
This is n for which M = 10. So
Rounding up
The manager should use a sample size of 12 to determine the average travel expenditure