Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 8: Q 72. (page 542)

Fruit fly thorax lengths Fruit flies are used frequently in genetic research because of their quick reproductive cycle. The length of the thorax (in millimeters) was measured for each fly in a random sample of 49male fruit flies. The mean length was x¯=0.8004mm, with a standard deviation of sX=0.0782mmmm. Construct and interpret a 90%confidence interval for the true mean thorax length of a male fruit fly.

Short Answer

Expert verified

Required confidence interval is(0.7817,0.8191)

Step by step solution

01

Given Information

It is given that n=14

(x¯)=0.8004

sx=0.0782

02

Concept Used

Formula to be used isx¯-ta2,n-1×sn<μ<x¯+ta2,n-1×sn

03

Calculation

  • In MINTAB Sheet, enter data set.
  • Press Stat>Basic Statistics>1-Sample t.
  • Choose summarized data. Enter given values.
  • Check options and enter 90%in confidence level.
  • Press OK.

Output obtained is:

Confidence Interval is (0.7817,0.8191)

There is 95%confidence that true mean length lies between0.7817and0.8191

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.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

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

Oranges A home gardener likes to grow various kinds of citrus fruit. One of his

mandarin orange trees produces oranges whose circumferences follow a Normal

distribution with mean 21.1cm and standard deviation 1.8cm.

a. What is the probability that a randomly selected orange from this tree has a

circumference greater than 22cm?

b. What is the probability that a random sample of 20 oranges from this tree has a mean circumference greater than 22 cm?

Engine parts A random sample of 16 of the more than 200auto engine crankshafts produced in one day was selected. Here are measurements (in millimeters) of a critical component on these crankshafts:

a. Construct and interpret a 95%confidence interval for the mean length of this component on all the crankshafts produced on that day.

b. The mean length is supposed to be μ=224mm but can drift away from this target during production. Does your interval from part (a) suggest that the mean has drifted from 224mm? Explain your answer.

Teens and their TV sets According to a Gallup Poll report, 64%of teens aged 13to 17have TVs in their rooms. Here is part of the footnote to this report:

These results are based on telephone interviews with a randomly selected national sample of 1028teenagers in the Gallup Poll Panel of households, aged 13to 17. For results based on this sample, one can say that the maximum error attributable to sampling and other random effects is ±3percentage points. In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.

a. We omitted the confidence level from the footnote. Use what you have learned to estimate the confidence level, assuming that Gallup took an SRS.

b. Give an example of a “practical difficulty” that could lead to bias in this survey.

School vouchers A small pilot study estimated that 44%of all American

adults agree that parents should be given vouchers that are good for education at any public or private school of their choice.

a. How large a random sample is required to obtain a margin of error of at most 0.03with 99%confidence? Answer this question using the pilot study’s result as the guessed value for p^

b. Answer the question in part (a) again, but this time use the conservative guessp^=0.5. By how much do the two sample sizes differ?

Critical values What critical value t*from Table B should be used for a

confidence interval for the population mean in each of the following situations?

a. A 95% confidence interval based on n=10 randomly selected observations

b. A99% confidence interval from an SRS of 20 observations

c. A 90% confidence interval based on a random sample of 77 individuals
See all solutions

Recommended explanations on Math Textbooks

Discrete Mathematics

Read Explanation

Logic and Functions

Read Explanation

Probability and Statistics

Read Explanation

Applied Mathematics

Read Explanation

Mechanics Maths

Read Explanation

Geometry

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.

Sign-up for free