Questions from Statistics Principles

Q: According to the American Time Use Survey, adult Americans spent 42

According to the American Time Use Survey, adult Americans spent 42.6 minutes per day on phone calls and answering or writing email in 2006. (a) Suppose that we want to judge whether the amount of dai...

Q: The trade magazine QSR routinely examines fast-food drive-thru

The trade magazine QSR routinely examines fast-food drive-thru service times. Their recent research indicates that the mean time a car spends in a McDonald’s drive- thru is 167.1 seconds. A McDonal...

Q: “Did you get your 8 hours of sleep last night?”

“Did you get your 8 hours of sleep last night?” is a common question. In a recent survey of 151 postpartum women, the folks at the National Sleep Foundation found that the mean sleep time was 7.8 hour...

Q: The outside diameter of a manufactured part must be 1.3825

The outside diameter of a manufactured part must be 1.3825 inches, according to customer specifications. The data shown represent a random sample of ten parts. Use a 95% confidence interval to judge w...

Q: In many parliamentary procedures, a supermajority is defined as an excess

In many parliamentary procedures, a supermajority is defined as an excess of 60% of voting members. In a poll conducted by the Gallup organization on May 10, 1939, 1561 adult Americans were asked, “Do...

Q: A Zone diet is one with a 40%–30%–30

A Zone diet is one with a 40%–30%–30% distribution of carbohydrate, protein, and fat, respectively, and is based on the book Enter the Zone. In a study conducted by researchers Christopher Gardner and...

Q: According to the Pew Research Center, the proportion of the American

According to the Pew Research Center, the proportion of the American population who use only a cellular telephone (no landline) is 0.37. Jason conducts a survey of thirty 20- to 24-year-olds who live...

Q: A stock analyst wants to know if there is a difference between

A stock analyst wants to know if there is a difference between the mean rate of return from energy stocks and that from financial stocks. He randomly selects 13 energy stocks and computes the rate of...

Q: Zoloft is a drug used to treat obsessive-compulsive disorder (

Zoloft is a drug used to treat obsessive-compulsive disorder (OCD). In randomized, double-blind clinical trials, 926 patients diagnosed with OCD were randomly divided into two groups. Subjects in grou...

Q: Does hypnotism result in a different success rate for men and women

Does hypnotism result in a different success rate for men and women who are trying to quit smoking? Researchers at Science magazine analyzed studies involving 5600 male and female smokers. Of the 2800...