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Null and alternative hypotheses, Probability

1) The EPA fuel economy rating says that the Toyota Prius hybrid car gets 48 mpg on the highway. Deborah wonders whether the actual long-term average highway mileage of her new Prius is less than 48 mpg. She keeps careful records of gas milegae for 3000 miles of highway driving. Her result is x̄ = 47.2 mpg. What are her
null and alternative hypotheses?

2) The average amount of time that high school students spend on homework is about 5 hours per week. Only 25% of college freshman say they spent at least 6 hours per weekon homework in highschool. Your college wonders if the average for its freshman differs from the national average. A random sample of 500 freshman claims to have spent an average of x̄ = 6.2 hours per week on homework in highschool. State the null and alternative hypotheses for a comparison of freshman at your college
with national freshman.

3) Internet search sites compete for users because they sell advertising space on their sites and can change more if they are heavily used. Choose an internet search attempt at random. Here is the probability distribution for the site the search uses:

Site Google Yahoo MSN Ask.com Others
Probability 0.66 0.21 0.07 0.04 ?

a) What is the probability that a search attempt is made at a site other than the leading four.

b) What is the probability that a search attempt is directed to a site other than Google?


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