Identifying Type I and Type II Errors In Exercises 31–36, describe type I and type II errors for a hypothesis test of the indicated claim.


Phone Repairs A cell phone repair shop advertises that the mean cost of repairing a phone screen is less than \$120.

In Problems 13–20, (a) state the null and alternative hypotheses in words, (b) state the null and alternative hypotheses symbolically, (c) explain what it would mean to make a Type I error, and (d) explain what it would mean to make a Type II error.

Pizza Historically, the time to order and deliver a pizza at Jimbo’s pizza was 48 minutes. Jim, the owner, implements a new system for ordering and delivering pizzas that he believes will reduce the time required to get a pizza to his customers.

If the consequences of making a Type I error are severe, would you choose the level of significance, α, to equal 0.01, 0.05, or 0.10? Why?

What happens to the probability of making a Type II error, β, as the level of significance, α, decreases? Why?

Identifying Type I and Type II Errors In Exercises 31–36, describe type I and type II errors for a hypothesis test of the indicated claim.

Security A campus security department publicizes that at most 25% of applicants become campus security officers.

In Exercises 7–10, describe type I and type II errors for a hypothesis test of the claim.

An energy bar maker claims that the mean number of grams of carbohydrates in one bar is less than 25.

"Simulation Simulate drawing 100 simple random samples of size n = 40 from a population whose proportion is 0.3.

d. How do we know that a rejection of the null hypothesis results in making a Type I error in this situation?"

True or False? In Exercises 5–10, determine whether the statement is true or false. If it is false, rewrite it as a true statement.

A statistical hypothesis is a statement about a sample.

Getting at the Concept Explain why a level of significance of α=0 is not used.