Question

Q1:A research study claims that the average mean that the kids start walking is almost 13 months. A researcher want to check if the claim is true or false. A random sample of 20 kids was selected randomly, with average mean and standard deviation 14 and 1 month respectively. Check whether the hypothesis is true or false give that t-tabulated =2.093

Q2: Resolve q1 if the sample size is 40

Q3:Suppose a sample of 16 light trucks is randomly selected off the assembly line. The trucks are driven 1000 miles and the fuel mileage (MPG) of each truck is recorded. It is found that the mean MPG is 22 with a SD equal to 3. The previous model of the light truck got 20 MPG.

Questions:

• State the null hypothesis for the problem above

• Conduct a test of the null hypothesis at p = .05. BE SURE TO PROPERLY STATE YOUR STATISTICAL CONCLUSION.

• Provide an interpretation of your statistical conclusion using the variables from the description given

Answer 1

Q1)

Here we have to test that

Null hypothesis:

Alternative hypothesis:

where

n = sample size = 20

Sample mean = = 14

Sample standard deviation = s = 1

Here population standard deviation is not given and n = 20 < 30 so we use t test.

Test statistic:

t = 4.472 (Round to 3 decimal)

Test statistic = t = 4.472

Given that t critical value = 2.093

Test is two tailed test.

Here t=4.472 > 2.093

So we reject H0.

Conclusion: There is sufficient evidence to support the claim that the average mean that the kids start walking is almost 13 months.