American Idol Contestants on the TV show American Idol competed to win a singing contest. At one point, the website WhatNotToSing.com listed the actual numbers of eliminations for different orders of singing, and the expected number of eliminations was also listed. The results are in the table below. Use a 0.05 significance level to test the claim that the actual eliminations agree with the expected numbers. Does there appear to be support for the claim that the leadoff singers appear to be at a disadvantage?

Singing Order

1

2

3

4

5

6

7–12

Actual Eliminations

20

12

9

8

6

5

9

Expected Eliminations

12.9

12.9

9.9

7.9

6.4

5.5

13.5

Short Answer

Expert verified

There is not enough evidence to conclude thatthe actual number of eliminations is not the same as the expected number of eliminations.

Since the actual number of eliminations for the lead-off singers is 20 and the expected eliminations should have been 12.9, it can be said that the lead-off singers appear to be at a disadvantage.

Step by step solution

01

Given information

The actual number and the expected number of eliminations are tabulated for different orders for singing.

02

Hypotheses

The null hypothesis is as follows:

The actual number of eliminations is the same as the expected number of eliminations.

The alternative hypothesis is as follows:

The actual number of eliminations is not the same as the expected number of eliminations.

It is considered a right-tailed test.

If the test statistic value is greater than the critical value, then the null hypothesis is rejected, otherwise not.

03

Observed and expected frequencies

Observed Frequency:

The frequencies provided in the table are the observed frequencies. They are denoted by\(O\).

The following table shows the observed frequency for each order:

\({O_1}\)=20

\({O_2}\)=12

\({O_3}\)=9

\({O_4}\)=8

\({O_5}\)=6

\({O_6}\)=5

\({O_{7 - 12}}\)=9

Expected Frequency:

The expected frequencies are also tabulated in the problem. The values are written below:

\({E_1}\)=12.9

\({E_2}\)=12.9

\({E_3}\)=9.9

\({E_4}\)=7.9

\({E_5}\)=6.4

\({E_6}\)=5.5

\({E_{7 - 12}}\)=13.5

04

Test statistic

The test statistic is computed as shown below:

\[\begin{aligned}{c}{\chi ^2} = \sum {\frac{{{{\left( {O - E} \right)}^2}}}{E}\;\;\; \sim } {\chi ^2}_{\left( {k - 1} \right)}\\ = \frac{{{{\left( {20 - 12.9} \right)}^2}}}{{12.9}} + \frac{{{{\left( {12 - 12.9} \right)}^2}}}{{12.9}} + ....... + \frac{{{{\left( {9 - 13.5} \right)}^2}}}{{13.5}}\\ = 5.624\end{aligned}\]

Thus, \({\chi ^2} = 5.624\).

05

Obtain critical value, p-value and determine the conclusion of the test

The degrees of freedom are computed below:

\(\begin{aligned}{c}df = \left( {k - 1} \right)\\ = \left( {7 - 1} \right)\\ = 6\end{aligned}\)

The critical value of\({\chi ^2}\)for 6 degrees of freedom at 0.05 level of significance for a right-tailed test is equal to 12.5916.

The corresponding p-value is approximately equal to 0.466598.

Since the value of the test statistic is less than the critical value and the p-value is greater than 0.05, the null hypothesis is failed to reject.

There is not enough evidence to conclude thatthe actual number of eliminations is not the same as the expected number of eliminations.

Since the actual number of eliminations for the lead-off singers is 20 and the expected eliminations should have been 12.9, it can be said that the lead off singers appear to be at a disadvantage.

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 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

Equivalent Tests A\({\chi ^2}\)test involving a 2\( \times \)2 table is equivalent to the test for the differencebetween two proportions, as described in Section 9-1. Using the claim and table inExercise 9 “Four Quarters the Same as $1?” verify that the\({\chi ^2}\)test statistic and the zteststatistic (found from the test of equality of two proportions) are related as follows:\({z^2}\)=\({\chi ^2}\).

Also show that the critical values have that same relationship.

Chocolate and Happiness In a survey sponsored by the Lindt chocolate company, 1708 women were surveyed and 85% of them said that chocolate made them happier.

a. Is there anything potentially wrong with this survey?

b. Of the 1708 women surveyed, what is the number of them who said that chocolate made them happier?

Do World War II Bomb Hits Fit a Poisson Distribution? In analyzing hits by V-1 buzz bombs in World War II, South London was subdivided into regions, each with an area of 0.25\(k{m^2}\). Shown below is a table of actual frequencies of hits and the frequencies expected with the Poisson distribution. (The Poisson distribution is described in Section 5-3.) Use the values listed and a 0.05 significance level to test the claim that the actual frequencies fit a Poisson distribution. Does the result prove that the data conform to the Poisson distribution?

Number of Bomb Hits

0

1

2

3

4

Actual Number of Regions

229

211

93

35

8

Expected Number of Regions

(from Poisson Distribution)

227.5

211.4

97.9

30.5

8.7

Probability Refer to the results from the 150 subjects in Cumulative Review Exercise 5.

a.Find the probability that if 1 of the 150 subjects is randomly selected, the result is a woman who spent the money.

b.Find the probability that if 1 of the 150 subjects is randomly selected, the result is a woman who spent the money or was given a single 100-yuan bill.

c.If two different women are randomly selected, find the probability that they both spent the money.

A study of people who refused to answer survey questions provided the randomly selected sample data shown in the table below (based on data from “I Hear You Knocking But You Can’t Come In,” by Fitzgerald and Fuller, Sociological Methods and Research,Vol. 11, No. 1). At the 0.01 significance level, test the claim that the cooperation of

the subject (response or refusal) is independent of the age category. Does any particular age group appear to be particularly uncooperative?

Age


18-21

22-29

30-39

40-49

50-59

60 and over

Responded

73

255

245

136

138

202

Refused

11

20

33

16

27

49

See all solutions

Recommended explanations on Math Textbooks

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