Practice Problems 8
is a national chain that prepares income tax returns for
The president of the company wants an average number of 5
customers per clerk per day.
On April 15, a random sample of 64 clerks shows
the average number of customers per clerk at 4.75.
Assume that the overall
standard deviation of 1.15.
Test whether the average number of customers per clerk on April 15 was 5 or
it was different.
Suppose the actual overall average number of customers per clerk on April 15
Was the decision you made in part (a) correct?
If not, what type of error
has been made?
What is the p-value of the test in part (a)
obtained in part (c)
, would you accept or reject the null
hypothesis from part (a) at
In its advertising,
claims that the overall average bill for its
services does not exceed $75.
A consumer agency obtains a random sample of 20
tax returns prepared by the company and finds the average preparation bill for
those 20 to be $79.82 with a sample standard deviation of $10.30.
amounts of the service fees are normally distributed.)