A recent study found that 51 children who watched a commercial for Walker Crisps (potato chips) featuring a long-standing sports celebrity endorser ate a mean of 36 grams of Walker Crisps as compared to a mean of 25 g of Walker Crisps for 41 children who watched a commercial for an alternative food snack. Suppose that the sample standard deviation for the children who watched the sports celebrity–endorsed Walker Crisps commercial was 21.4 g and the sample standard deviation for the children who watched the alternative food snack commercial was 12.8 g. Assuming the population variances are not equal and alpha-05, is there any evidence that the mean amount of Walker Crisps eaten was significantly higher for the children who watched the sports celebrity- endorsed Walker Crisps commercial?
1. What is the claim from the question? What are Null and Alternative Hypothesis for this problem?
2. What kind of test do you want to use?
3. Calculate Test Statistics.
4. Find P-value.
5. What is the conclusion that you could make?

Respuesta :

Answer:

1

The claim is that the mean amount of Walker Crisps eaten was significantly higher for the children who watched the sports celebrity- endorsed Walker Crisps commercial

2

The kind of test to use is a t -test because a t -test is used to check if there is a difference between means of a population

3

[tex]t = 3.054[/tex]

4

The p-value  is   [tex]p-value = P(Z > 3.054) = 0.0011291[/tex]

5

The conclusion is  

There is sufficient evidence to conclude that the mean amount of Walker Crisps eaten was significantly higher for the children who watched the sports celebrity- endorsed Walker Crisps commercial

The test statistics is  

Step-by-step explanation:

From the question we are told that

   The first sample size is  [tex]n_1 = 51[/tex]

    The first sample  mean is [tex]\mu_1 = 36[/tex]

    The second sample size is  [tex]n_2 = 41[/tex]

    The second sample  size is  [tex]\mu_2 = 25[/tex]

     The first standard deviation is  [tex]\sigma _1 = 21.4 \ g[/tex]

    The second standard deviation is  [tex]\sigma _2 = 12.8 \ g[/tex]

  The  level of significance is  [tex]\alpha = 0.05[/tex]

The  null hypothesis is  [tex]H_o : \mu_1 = \mu_ 2[/tex]

The  alternative hypothesis is  [tex]H_a : \mu_1 > \mu_2[/tex]

Generally the test statistics is mathematically represented as

    [tex]t = \frac{\= x_1 - \= x_2}{ \sqrt{ \frac{s_1^2}{n_1} + \frac{s_2^2}{n_2} } }[/tex]

=>   [tex]t = \frac{ 36 - 25}{ \sqrt{ \frac{ 21.4^2}{51} + \frac{ 12.8^2}{41} } }[/tex]

=> [tex]t = 3.054[/tex]

The  p-value is mathematically represented as

     [tex]p-value = P(Z > 3.054)[/tex]

Generally from the z table  

             [tex]P(Z > 3.054) = 0.0011291[/tex]

=>   [tex]p-value = P(Z > 3.054) = 0.0011291[/tex]

From the values obtained  we see that [tex]p-value < \alpha[/tex] so  the null hypothesis is rejected

Thus the conclusion is  

  There is sufficient evidence to conclude that the mean amount of Walker Crisps eaten was significantly higher for the children who watched the sports celebrity- endorsed Walker Crisps commercial

The value of the difference in the mean number of chips eaten can be used to test the hypothesis.

The correct responses are;

  • 1. The claim is that children that watched the given commercial ate more Walker Crisps potato chips than others.
  • The null hypothesis is [tex]\underline {H_0; \ \overline x_1 = \overline x_2}[/tex] , the alternative hypothesis is,  [tex]\underline{H_a; \ \overline x_1 > \overline x_2}[/tex]
  • 2. The kind of test to use is a t-test
  • 3. The test statistic is approximately 3.054
  • 4. The p-value is; 0.001 < p-value < 0.0025
  • 5. Reject the null hypothesis, there is significant statistical evidence to suggest that the children that watched the commercial ate more Walter Crisps potato chips than children that watched the commercial for an alternative snack.

Reasons:

The given parameters are;

The amount of Walker Crisps potato chips children ate, based on commercial watched.

Celebrity endorsed food snack commercial mean, [tex]\overline x_1[/tex] = 36 g

Sample size that watched the celebrity endorsed commercial, n₁ = 51

Alternative food snack commercial mean, [tex]\overline x_2[/tex] = 25 g

Sample size that watched the other commercial = 41

Standard deviation, SD,  of the samples;

Sample that watched the celebrity endorsed commercial, SD₁ = 21.4 g

Sample that watched the other commercial, SD₂ = 12.8 g

Reasons:

1. The claim from the question is; The mean amount of Walker Crisp eaten was significantly higher for the children who watched the sports celebrity - endorsed Walker Crisps commercial.

The null hypothesis is, H₀; [tex]\overline x_1 = \overline x_2[/tex] (There is no difference in the mean)

The alternative hypothesis is, Hₐ; [tex]\overline x_1[/tex] > [tex]\overline x_2[/tex] (The mean of the amount of Walker Crisps eaten is significantly higher for the children that watched the sports celebrity-endorsed commercial)

2. Given that the aim of the study is to determine if the mean of the first

sample is higher than the mean of the second sample, the kind of test to

be performed is the test of the difference in the mean of the two samples

based on specified hypothesis, (one sample is higher), which is done using

a t-test, given that the population mean is not specified (unknown).

The kind of test to use is a t-test

3. The test statistic is given by Welch's Test for unequal variance as follows;

[tex]\displaystyle t = \mathbf{\frac{\overline x_1 - \overline x_2}{\sqrt{\dfrac{s_1^2}{n_1} +\dfrac{s_2^2}{n_2} } }}[/tex]

Which gives;

[tex]\displaystyle t = \frac{36- 25}{\sqrt{\dfrac{21.4^2}{51} +\dfrac{12.8^2}{41} } } = \frac{77500}{25379} \approx 3.054[/tex]

The test statistic, t ≈ 3.054

4. From the above test statistic and by finding, degrees of freedom, df as follows, the p-value can be found.

[tex]\displaystyle df = \mathbf{\frac{\left(\dfrac{s_1^2}{n_1} +\dfrac{s_2^2 \righ}{n_2} \right)^2}{\dfrac{1}{n_1 - 1} \cdot \left( \dfrac{s_1^2}{n_1} \right)^2 + \dfrac{1}{n_2 - 1} \cdot \left( \dfrac{s_2^2}{n_2} \right)^2}}[/tex]

Which gives;

[tex]\displaystyle df = \frac{\left(\dfrac{21.4^2}{51} +\dfrac{12.8^2 \righ}{41} \right)^2}{\dfrac{1}{51 - 1} \cdot \left( \dfrac{21.4^2}{51} \right)^2 + \dfrac{1}{41 - 1} \cdot \left( \dfrac{12.8^2}{41} \right)^2} \approx \mathbf{83.69}[/tex]

From the t-test table, we have the p-value of the result as follows;

The p-value is; 0.001 < P(t > 3.054) < 0.0025.

5. The conclusion that can be made is; Given that the p-value of the test

statistic is less than the given alpha value of 0.05, we reject the null

hypothesis, given that there is significant statistical evidence to show that

the mean amount of Walker Crisp eaten was significantly higher for the

children that watch the celebrity-endorsed Walker Crisps commercial.

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