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Christmas Presents. The Arizona Republic conducted a telephone poll of 758Arizona adults who celebrate Christmas. The question asked was, "In your family, do you open presents on Christmas Eve or Christmas Day?" Of those surveyed, 394said they wait until Christmas Day.

a. Determine and interpret the sample proportion.

b. At the 5%significance level, do the data provide sufficient evidence to conclude that a majority (more than 50%) of Arizona families who celebrate Christmas wait until Christmas Day to open their presents?

Short Answer

Expert verified

(a) The sample proportion is 0.52.

(b) At the 5%level, the test results are not statistically significant.

As a result, the data does not support the conclusion that the majority of Arizona Christmas-observant families wait until Christmas Day to unwrap their gifts.

Step by step solution

01

Part (a) Step 1: Given information

The significance level is 5%

x=394

n=758

02

Part (a) Step 2: Explanation

The sample proportion is expressed as

p^=xn

The sample proportion is calculated as

p^=394758

=0.52

As a result, the sample proportion is 0.52, indicating that the52% majority of Arizona families who celebrate Christmas wait until the day after the holiday to open their gifts.

03

Part (b) Step 1: Given information

The significance level is 5%

x=394

n=758

04

Part (b) Step 2: Explanation

Calculate the value ofnp0

np0=(758)(0.5)

=379

Calculate the value ofn1-p0

n1-p0=(758)(1-0.5)

=758(0.5)

=379

Both the values are greater than 5.

So one proportion z-test is appropriate to use.

The null hypothesis is

H0:p0=0.5

The alternate hypothesis is

H0:p0>0.5

The expression for zis

z=p^-p0p01-p0n

The z value is calculated as

z=0.52-0.50.5(1-0.5)758

=0.020.018

=1.09

And also α=0.05, the critical value of zfrom the standard table is

z0.05=1.645

Because the test is a right-tailed test, a positive value is used.

The test statistic is within acceptable bounds. As a result, the hypothesis H0is not ruled out.

At the 5%level, the test results are not statistically significant.

As a result, the data does not support the conclusion that the majority of Arizona Christmas-observant families wait until Christmas Day to unwrap their gifts.

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Most popular questions from this chapter

Suppose that you are using independent samples to compare two population proportions.

Fill in the blanks.

a. The mean of all possible differences between the two sample proportions equals the

b. For large samples, the possible differences between the two sample proportions have approximately a distribution.

Margin of error=0.04

Confidence level=99%

Educated guess=0.3

(a) Obtain a sample size that will ensure a margin of error of at most the one specified (provided of course that the observed value of the sample proportion is further from 0.5that of the educated guess.

(b). Compare your answer to the corresponding one and explain the reason for the difference, if any.

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