Stats Help for College-level Students

Word Problem

At the time Beth was hired as a server at a Restaurant, she was told she could average $20 a day in tips. Over the first 35 days she was employed at the restaurant, the mean daily amount of her tips was $24.85 with a standard deviation of $3.24. At the .01 significance level, can Beth conclude that she is earning an average of ...continues

Statistics word problem - testing hypothesis

Fast Service, a chain of automotive tune-up shops, advertises that its personnel can change the oil, replace the oil filter, and lubricate any standard automobile in 15 minutes, on the average. The National Business Bureau received complaints from customers that service takes considerably longer. To check the fast service claim, ...continues

Word Problem - calculating P-value and F test

One reads that a business school graduate with an undergrad degree earns more than a high school grad with no additional ed, and a person with a master's or a doctorate earns even more. To test this a random sample of 25 executives from compainies with assests over 1 million were selected. Their incomes, classified by highes ...continues

Null and Alternative Hypothesis

A vending machine that dispenses coffee into cups must fill the cups with 7.8oz of liquid. Before selling the vending machine to a college or business, the company tests the machine to be sure it is dispensing an average amount of 7.8oz of coffee. A sample of 20 amounts is shown below. The amount of coffee dispensed is assumed ...continues

Null and Alternative Hypothesis. Set up the null and alternative hypothesis to be tested.

a. A company is thinking about setting up an onsite daycare program for its employees. The CEO has stated that she will do so only if more than 80% of the employees favor such a decision. Set up the null and alternative hypothesis to be tested. b. You are a connoisseur of chocolate chip cookies and you do not think that N ...continues

Null and Alternative Hypothesis

10.21 An automobile company thinks that with new designs, it scars will last longer before having a problem. For this reason the company wishes to extend the warranty that comes with the vehicle in hopes of attracting more customers. Before making this change the idea is tested. Prior to the design changes, the cars lasted on th ...continues

Null and Alternative Hypotheses

In an attempt to improve quality many manufacturers are developing partnerships with their suppliers. A local fast food burger outfit has partnered with its supplier of potatoes. The burger outfit buys potatoes in bags that weigh 20 lbs. It does not wish to accept underweight bags of potatoes. A sample of 40 bags shows an ave ...continues

Statistics - polling

1. On February 8, 2002, the Gallup Organization released the results of a poll concerning American attitudes toward the 19th Winter Olympics in Salt Lake City, Utah. The poll results were based on telephone interviews with a randomly selected national sample of 1011 adults, 18 years and older, conducted February 4 - 6, 2002. ...continues

Null and Alternative Hypothesis

The educational testing service (ETS) designs and administers the SAT exams. Recently the format of the exam changed and the claim has been made that the new exam can be completed in an average time of 120 minutes. A sample of 50 new exam times yielded an average time of 115 min. The standard deviation is assumed to be 2 minu ...continues

Word Problem

A stockbroker at Critical Securities reorted the mean rate of return on a smaple of 10 oil stocks was 12.6 percent with a standard deviation of 3.9%. The mean rate of return on a sample of 8 utility stocks was 10.9% with a standard deviation of 3.5%. At the .05 significance level, can we conclude that there is a more variation ...continues