Stating hypotheses

a. A change is made that should improve student satisfaction with the parking situation at a local high school. Before the change, 37%of students approve of the parking that's provided. The null hypothesis H0:p>0.37H0:p>0.37is tested against the alternative Ha: p=0.37Ha:p=0.37

b. A researcher suspects that the mean birth weights of babies whose mothers did not see a doctor before delivery is less than 3000 grams. The researcher states the hypotheses as

H0:x-=3000grams-5H0:x¯=3000grams

Ha: x-<3000grams Ha:x¯<3000grams

explain what's wrong with the stated hypotheses. Then give correct hypotheses.

Short Answer

Expert verified

The correct hypotheses are listed as:

Part (a)H0:p=0.37,Ha:p>0.37

Part (b)H0:p=0.3000grams, Ha:p<0.3000grams

Step by step solution

01

Part (a) Step 1:Given information

The null hypothesisH0:p>0.37H0:p>0.37is tested against the alternative

Ha:p=0.37Ha:p=0.37

02

Part (b) Step 2:Explaination

The null hypothesis given by the following expression:

H0:p^=0.37

And the alternate hypothesis is given by the following expression:

Ha:p^0.37

Now, know that the hypotheses always used the population value not the sample value. So the sample values stated in the null hypothesis and alternate hypothesis should be remove and replaced by population value.

The correct hypotheses are listed as:

H0:p=0.37

Ha:p>0.37

Hence, there is use population value not the sample value in hypotheses.

03

Part (b)Step 2:Given information

H0:x-=3000gramsH0:x¯=3000grams

Ha:x-<3000gramsHa:x¯<3000grams

04

Part (b) Step 2:Explaination

The null hypothesis given by the following expression:

H0:x¯=0.3000grams

And the alternate hypothesis is given by the following expression:

Ha:x¯<0.3000grams

Now, know that the hypotheses always used the population value not the mean value. So the sample values stated in the null hypothesis and alternate hypothesis should be remove and replaced by population value.

The correct hypotheses are listed as:

H0:p=0.3000grams

Ha:p<0.3000grams

Hence, there is use population value not the sample value in hypotheses.

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Most popular questions from this chapter

Significance tests A test of Ho:p=0.5versus Ha:p>0.5based on

a sample of size 200yields the standardized test statistic z=2.19. Assume that the conditions for performing inference are met.

a. Find and interpret the P-value.

b. What conclusion would you make at the α=0.01 significance level? Would

your conclusion change if you used α=0.05 instead? Explain your reasoning.

c. Determine the value of p^= the sample proportion of successes.

A government report says that the average amount of money spent per U.S. household per week on food is about \(158. A random sample of50 households in a small city is selected, and their weekly spending on food is recorded. The sample data have a mean of \)165 and a standard deviation of \(20. Is there convincing evidence that the mean weekly spending on food in this city differs from the national figure of \)158?

Candy! A machine is supposed to fill bags with an average of 19.2 ounces of candy. The manager of the candy factory wants to be sure that the machine does not consistently underfill or overfill the bags. So the manager plans to conduct a significance test at the α=0.10significance level of

H0:μ=19.2Ha:μnotequalto19.2

where μ=the true mean amount of candy (in ounces) that the machine put in all bags filled that day. The manager takes a random sample of 75 bags of candy produced that day and weighs each bag. Check if the conditions for performing the test are met.

Fast connection? How long does it take for a chunk of information to travel

from one server to another and back on the Internet? According to the site

internettrafficreport.com, the average response time is 200 milliseconds (about one-fifth of a second). Researchers wonder if this claim is true, so they collect data on response times (in milliseconds) for a random sample of 14 servers in Europe. A graph of the data reveals no strong skewness or outliers.

a. State an appropriate pair of hypotheses for a significance test in this setting. Be sure to define the parameter of interest.

b. Check conditions for performing the test in part (a).

c. The 95% confidence interval for the mean response time is 158.22 to 189.64

milliseconds. Based on this interval, what conclusion would you make for a test of the hypotheses in part (a) at the 5% significance level?

d. Do we have convincing evidence that the mean response time of servers in the United States is different from 200 milliseconds? Justify your answer.

Attitudes Refer to Exercise 4. In the study of older students’ attitudes, the sample mean SSHA score was 125.7 and the sample standard deviation was 29.8. A significance test yields a P-value of 0.0101.

a. Explain what it would mean for the null hypothesis to be true in this setting.

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