Statistics

posted by .

A large television repair service claims that its average repair charge is $124. Suspecting that the average charge is higher, a consumer group randomly choose a sample of 35 statements for tv repairs done by the repair service and found the mean was $125.50 and s = 2.25. Test the claim at the .05 level of significance

  • Statistics -

    Use a one-sample z-test.

    Hypotheses:
    Ho: µ = 124 -->null hypothesis
    Ha: µ > 124 -->alternate hypothesis

    z = (sample mean - population mean)/(standard deviation divided by the square root of the sample size)

    With your data:
    z = (125.50 - 124)/(2.25/√35) = ?

    Finish the calculation.

    Check a z-table at .05 level of significance for a one-tailed test.
    If the z-test statistic exceeds the critical value from the z-table, reject the null. If the z-test statistic does not exceed the critical value from the z-table, do not reject the null.

    I hope this will help get you started.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. math

    A small business just leased a new computer and color laser printer for three years. The service contract for the the computer offers unlimited repairs for a fee of $100 a year plus a $25 service charge for each repair needed. The …
  2. statistics

    You are the owner of an auto repair service. History tells you it takes on average 45 minutes to complete a repair job. You have determined the standard deviation for a job is 6 minutes. A women comes into your shop and tells you she …
  3. Probability

    You are the owner of an auto repair service. History tells you it takes on average 45 minutes to complete a repair job. You have determined the standard deviation for a job is 6 minutes. A women comes into your shop and tells you she …
  4. statistics

    An appliance repair shop owner has fitted the quadratic trend equation ŷ = 90 + 0.9x + 3x² to a time series of annual repair orders, with y= the number of repair orders and x= 1 for 2000. Forecast the number of repair orders …
  5. stats

    An automobile repair shop has determined that the average service time on an automobile is 2 hours with a standard deviation of 32 minutes. A random sample of 64 out of 400 services is selected. What is the probability that this sample …
  6. Statistics

    A recent article in the Myrtle Beach Sun Times reported that the mean labor cost to repair a color television is $90 with a standard deviation of $22. Monte’s TV Sales and Service completed repairs on two sets this morning. The labor …
  7. Operations management

    An appliance manufacturer wants to contract with a repair shop to handle authorized repairs. The company has an acceptable range of repair time from 50 minutes to 90 minutes. Two firms have submitted bids for the work. In the evaluation …
  8. Statistics

    Computer Depot is a large store that sells and repairs computers. A random sample of 110 computer repair jobs took technicians an average of 93.2 minutes per computer. Assume that o is known to be 16.9 minutes. Find a 99% confidence …
  9. Statistics

    A computer repair service found that a random sample of 45 repair costs had a mean cost of $659. Assume that the population standard deviation is $125. Calculate the margin of error, E, for a 95% confidence interval for the population …
  10. Algebra

    a car repair shop charge $80 per hour for labor and $210 for the parts of a car . if the total cost of repair for the car was $490 , how many hours did it take ro repair the car ?

More Similar Questions