A data set consists of 40 observations. For a quantitative variable, how many classes
would you recommend for the frequency distribution?
A silkscreen printing company purchases t-shirts. To ensure the quality of the shipment,
300 t-shirts are randomly selected. Fifteen are defective. What is the estimated
proportion defective in the population?
One of the major U.S. tire makers wishes to review its warranty for their rainmaker tire.
The warranty is for 40,000 miles. The distribution of tire wear is normally distributed
with a population standard deviation of 15,000 miles. The tire company believes that
the tire actually lasts more than 40,000 miles. A sample of 49 tires revealed that the
mean number of miles is 45,000 miles. If we test the hypothesis with a 0.05
significance level, what is the probability of a Type II error if the actual true tire
mileage is 42,000 miles?
In a study of protein breakfast bars, five bars from each of three brands were tested to
see if the mean amount of protein per bar differs among the brands. If the error sum of
squares is 0.09, the mean square error is _____.
A study by a bank compared the mean savings of customers who were depositors for
three years or less with those who had been depositors for more than three years. The
results of a sample are as follows.
Assuming that the financial officer wants to show that there is a difference in the
average savings balance between the two classes of depositors, the null hypothesis is
____________.