Chapter 10: Q.1.3 (page 608)
Find the probability that is less than or equal to . Show your work.
Short Answer
The required probability is .
Chapter 10: Q.1.3 (page 608)
Find the probability that is less than or equal to . Show your work.
The required probability is .
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Get started for freeThirty randomly selected seniors at Council High School were asked to report the age (in years) and mileage of their main vehicles. Here is a scatterplot of the data:
(a) What is the equation of the least-squares regression line? Be sure to define any symbols you use.
(b) Interpret the slope of the least-squares line in the context of this problem. (c) One student reported that her -year-old car had miles on it. Find the residual for this data value. Show your work
Paired or unpaired? In each of the following settings, decide whether you should use paired t procedures or two-sample t procedures to perform inference. Explain your choice.
(a) To test the wear characteristics of two tire brands, A and B, each brand of tire is randomly assigned to 50 cards of the same make and model.
(b) To test the effect of background music on productivity, factory workers are observed. For one month, each subject works without music. For another month, the subject works while listening to music on an MP3 player. The month in which each subject listens to music is determined by a coin toss.
(c) A study was designed to compare the effectiveness of two weight-reducing diets. Fifty obese women who volunteered to participate were randomly assigned into two equal-sized groups. One group used Diet \(A\) and the other used Diet B. The weight of each woman was measured before the assigned diet and
41. Literacy rates Do males have higher average literacy rates than females in Islamic countries? The table below shows the percent of men and women at least years old who were literate in in the major Islamic nations. (We omitted countries with populations of less thanmillion.) Data for a few nations, such as Afghanistan and Iraq, were not available.
A surprising number of young adults (ages to ) still live in their parents’ homes. A random sample by the National Institutes of Health included men and women in this age group. The survey found that of the men and of the women lived with their parents.
(a) Construct and interpret a confidence interval for the difference in population proportions (men minus women).
(b) Does your interval from part (a) give convincing evidence of a difference between the population proportions? Explain.
A driving school wants to find out which of its two instructors is more effective at preparing students to pass the state’s driver’s license exam. An incoming class of students is randomly assigned to two groups, each of size . One group is taught by Instructor A; the other is taught by Instructor B. At the end of the course, of Instructor A’s students and of Instructor B’s students pass the state exam. Do these results give convincing evidence that Instructor A is more effective?
Min Jae carried out the significance test shown below to answer this question. Unfortunately, he made some mistakes along the way. Identify as many mistakes as you can, and tell how to correct each one.
State: I want to perform a test of
where the proportion of Instructor A's students that passed the state exam and the proportion of Instructor B's students that passed the state exam. Since no significance level was stated, I'll use
Plan: If conditions are met, I’ll do a two-sample test for comparing two proportions.
Random The data came from two random samples of students.
- Normal The counts of successes and failures in the two groups , and are all at least .
- Independent There are at least 1000 students who take this driving school's class.
Do: From the data, and . So the pooled proportion of successes is
- Test statistic
localid="1650450621864"
- -value From Table A, localid="1650450641188" .
Conclude: The -value, , is greater than , so we fail to reject the null hypothesis. There is no convincing evidence that Instructor A's pass rate is higher than Instructor B's.
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