According to the Coffee Research Organization the typical American coffee drinke

Question

According to the Coffee Research Organization the typical American coffee drinker consumes an average of 3.1 cups per day, with a population standard deviation of 0.58 cups. After a new coffee campaign is launched by the coffee industry, marketers believe the amount of coffee consumed is now greater than 3.1 cups per day. State the null hypothesis and the alternative hypothesis. The level of significance is 0.05. Select the test statistic. Formulate the decision rule. Make a decision. Interpret the result. Are the marketers right?

Coffee Consumption

3.1

3.3

3.5

2.6

2.6

4.3

4.4

3.8

3.1

4.1

3.1

3.2

Coffee Consumption

3.1

3.3

3.5

2.6

2.6

4.3

4.4

3.8

3.1

4.1

3.1

3.2

Explanation / Answer

H0:mu=3.1 (Typical American coffee drinker consumes average 3.1 cup coffee per day)

H1:mu>3.1 (Typical American coffee drinker consumes more than 3.1 cup coffee per day)

The population standard deviation is knwon, use 1-sample Z test.

Z=(Xbar-mu)/(sigma/sqrt N), where Xbar and mu denote sample and population mean, sigm ai spopulation standard deviation and N is sample size.

=(3.425-3.1)/(0.58/sqrt 12)

=1.94

Compute p value. Reject null hypothesis if p value is less than alpha=0.05, otherwise not.

p value is 0.02619. Reject null hypothesis to cocnlude that after ne wcoffee campaign the typical American consumes more than 3.1 cup scoffeed per day.

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