/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Q.11 Who uses instant messaging? Do y... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 10: Q.11 (page 622)

Who uses instant messaging? Do younger people use online instant messaging (IM) more often than older people? A random sample of IM users found that 73of the 158people in the sample aged 18to 27said they used IM more often than email. In the 28to 39age group, 26of 143people used IM more often than email.9 Construct and interpret a 90% con铿乨ence interval for the difference between the proportions of IM users in these age groups who use IM more often than email.

Short Answer

Expert verified

From the given information,it could be interpreted that there is90%the probability that the difference in the proportion of IM users lies between 0.1959and0.3641

Step by step solution

01

Given Information

It is given in the question that,x1=73,n1=158,x2=26,n2=143

02

Explanation

The formula to compute the confidence interval for the difference in population proportion is :

CI=(p^1鈭�p^2)卤z伪/2脳p^1(1鈭�p^1)n1+p^2(1鈭�p^2)n2

The 95%confidence interval using Ti-83plus calculator is computed as:

Therefore, the confidence interval is (0.1959,0.3641)

03

Final Answer

Therefore, it could be interpreted that there is 90%probability that the difference in the proportion of IM users lies between 0.1959and0.3641

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Do drivers reduce excessive speed when they encounter police radar? Researchers studied the behavior of a sample of drivers on a rural interstate highway in Maryland where the speed limit was 55miles per hour. They measured the speed with an electronic device hidden in the pavement and, to eliminate large trucks, considered only vehicles less than 20feet long. During some time periods (determined at random), police radar was set up at the measurement location. Here are some of the data.

Number of vehiclesNumber over65mphNo radar12,9315,690Radar3,2851,051

(a) The researchers chose a rural highway so that cars would be separated rather than in clusters because some cars might slow when they see other cars slowing. Explain why this is important.

(b) Does the proportion of speeding drivers differ significantly when the radar is being used and when it isn鈥檛? Use information from the Minitab computer output below to support your answer.

The power takeoff driveline on tractors used in agriculture is a potentially serious hazard to operators of farm equipment. The driveline is covered by a shield in new tractors, but for a variety of reasons, the shield is often missing on older tractors. Two types of shields are the bolt-on and the flip-up. It was believed that the bolt-on shield was perceived as a nuisance by the operators and deliberately removed, but the flip-up shield is easily lifted for inspection and maintenance and may be left in place. In a study initiated by the U.S. National Safety Council, random samples of older tractors with both types of shields were taken to see what proportion of shields were removed. Of 183tractors designed to have bolt-on shields, 35 had been removed. Of the 136 tractors with flip-up shields, 15 were removed. We wish to perform a test of H0:pb-pif versus Ha:pb鈮�pf where pb and pf are the proportions of all tractors with the bolt-on and flip-up shields removed, respectively. Which of the following conditions for performing the appropriate significance test is definitely not satisfied in this case?

(a) Both populations are Normally distributed.

(b) The data come from two independent samples.

(c) Both samples were chosen at random.

(d) The counts of successes and failures are large enough to use Normal calculations.

(e) Both populations are at least 10 times the corresponding sample sizes

Shortly before the2008 presidential election, a survey was taken by the school newspaper at a very large state university. Randomly selected students were asked, 鈥淲hom do you plan to vote for in the upcoming presidential election?鈥� Here is a two-way table of the responses by political persuasion for 1850students:

Which of the following statements about these data is true?

(a) The percent of Republicans among the respondents is 41%.

(b) The marginal distribution of the variable choice of candidate is given by Obama: 55.6%; McCain: 37.6%; Other:1.1%; Undecided: 5.7%.

(c) About 11.2%of Democrats reported that they planned to vote for McCain.

(d) About 44.6%of those who are undecided are Independents.

(e) The conditional distribution of political persuasion among those for whom McCain is the candidate of choice is Democrat: 7.5%; Republican: 84.0%; Independent 18.8%:

Which of the following will increase the power of a significance test?

(a) Increase the Type喂喂error probability.

(b) Increase the sample size.

(c) Reject the null hypothesis only if the P-value is smaller than the level of significance.

(d) Decrease the significance level 伪.

(e) Select a value for the alternative hypothesis closer to the value of the null hypothesis.

A scatterplot and a least-squares regression line are shown in the figure below. If the labeled point P(20,24)is removed from the data set, which of the following statements is true ?

(a) The slope will decrease, and the correlation will decrease.

(b) The slope will decrease, and the correlation will increase.

(c) The slope will increase, and the correlation will increase.

(d) The slope will increase, and the correlation will decrease.

(e) No conclusion can be drawn since the other coordinates are unknown.
See all solutions

Recommended explanations on Math Textbooks

Geometry

Read Explanation

Pure Maths

Read Explanation

Applied Mathematics

Read Explanation

Discrete Mathematics

Read Explanation

Probability and Statistics

Read Explanation

Mechanics Maths

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.