Question

1.      Assuming the starting income new College graduates is normally distributed with a mean of $60,000 and standard deviation of $9,000.
A.        What is the probability of selecting a new College graduate at random and finding that he/she has a starting salary of less than $55,000?
B.      What proportion of new College graduates would be expected to have a starting salary of more than $48,000?
C.      What is the probability of randomly selecting a new College graduate with a starting salary between $60,000 and $75,000?
D.     What is the probability of selecting a new College graduate at random with a starting salary of less than $85,000?
E.      What percentage of new College graduates would be expected to have starting salaries between $50,000 and $70,000?

2.      Suppose a company wanted to know if there was a significant in the average income of its male and female customers.  Develop a null and alternate hypothesis for such a problem and give a conclusion based on the p-value results of .04.
Assume you are testing at the .05 level of significance.

3.      A company wants to know the useful life of a new revolutionary lightbulb it has just developed.  A mean of 64 of these bulbs revealed a mean useful life of 30,000 with a standard deviation of 1,500 hours.

A.      Use this information to develop a 95% confidence interval for the mean useful life of all new revolutionary lightbulbs.
B.      Use this information to develop a 98% confidence interval for the mean useful life of all new revolutionary lightbulbs.

4.      A pizza delivery company is concerned that it can no longer count on its average variable cost of $ 4.00 or less.  A sample of 36 pizzas revealed a variable cost of $4.05 and a standard deviation of $.25.  Testing at the .05 level of significance.  Develop null and alternate hypothesis for this claim and give a conclusion if your p-value is .06.

Answer 1