Chapter 10: Q.130 (page 610)
According to a recent study, U.S. companies have a mean maternity leave of six weeks
The given statement is a single proportion.
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Use the following information to answer the next 12 exercises: The U.S. Center for Disease Control reports that the mean life expectancy was 47.6 years for whites born in 1900 and 33.0 years for nonwhites. Suppose that you randomly survey death records for people born in 1900 in a certain county. Of the 124 whites, the mean life span was 45.3 years with a standard deviation of 12.7 years. Of the 82 nonwhites, the mean life span was 34.1 years with a standard deviation of 15.6 years. Conduct a hypothesis test to see if the mean life spans in the county were the same for whites and nonwhites.
In words, define the random variable of interest for this test.
Marketing companies have collected data implying that teenage girls use more ring tones on their cellular phones than
teenage boys do. In one particular study of 40 randomly chosen teenage girls and boys (20 of each) with cellular phones,
the mean number of ring tones for the girls was 3.2 with a standard deviation of 1.5. The mean for the boys was 1.7 with
a standard deviation of 0.8. Conduct a hypothesis test to determine if the means are approximately the same or if the girls’
mean is higher than the boys’ mean.
Use the following information to answer the next five exercises. A doctor wants to know if a blood pressure medication is effective. Six subjects have their blood pressures recorded. After twelve weeks on the medication, the same six subjects have their blood pressure recorded again. For this test, only systolic pressure is of concern. Test at the significance level.
What is the conclusion?
Use the following information to answer the next twelve exercises. In the recent Census, three percent of the U.S. population reported being of two or more races. However, the percent varies tremendously from state to state. Suppose that two random surveys are conducted. In the first random survey, out of 1,000 North Dakotans, only nine people reported being of two or more races. In the second random survey, out of 500 Nevadans, 17 people reported being of two or more races. Conduct a hypothesis test to determine if the population percents are the same for the two states or if the percent for Nevada is statistically higher than for North Dakota.
State the null and alternative hypotheses.
a.
b. :
A new prep class was designed to improve SAT test scores. Five students were selected at random. Their scores on two practice exams were recorded, one before the class and one after. The data recorded in the table given below. Are the scores, on average, higher after the class? Test at a level.
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