Stats

posted by .

It is known that the amount of time needed to change the oil in a car is normally distributed with a standard deviation of 5 minutes. A random sample of 100 oil changes yielded a sample mean of 22 minutes. Compute the 99% confidence interval estimate of the mean of the population.


Also determine the necessary sample size if you wish to be 99% confident and can tolerate an error of 1 minute.


Part 3 - With a sample size not exceeding 150 but everything else staying the same, what confidence level can be achieved?

95
96
97
98
still 99

This was answered in a previous post. For part 3, you can probably still use the same confidence interval.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Statistics

    It is known that the amount of time needed to change the oil in a car is normally distributed with a standard deviation of 5 minutes. A random sample of 100 oil changes yielded a sample mean of 22 minutes. Compute the 99% confidence …
  2. Statistics

    It is known that the amount of time needed to change the oil in a car is normally distributed. A random sample of 100 oil changes yielded a sample mean of 22 minutes and a standard deviation of 5 minutes. Then compared to the interval …
  3. Stats

    Suppose the time it takes for a purchasing agent to complete an online ordering process is normally distributed with a mean of 8 minutes and a standard deviation of 2 minutes. Suppose a random sample of 25 ordering processes is selected. …
  4. Stats

    A simple random sample will be obtained from a normally distributed population. Find the minimum sample size needed to be 99% confident that the sample standard deviation s is within 5% of the standard deviation. Is such a sample size …
  5. stats

    A final exam in Math 160 has a mean of 73 with standard deviation 7.73. Assume that a random sample of 24 students is selected and the test score of the sample is computed. Assuming the scores are normally distributed, what percentage …
  6. statistics

    from a normally distributed infinite number of iron bars lengths with a mean and standard deviation as 4 ft. and 0.6 ft. respectively, a sample of 100 bars is taken. if the sample mean is 4.2 ft., can the sample be called a truely …
  7. Stats

    the typical saturday the oil change facility will perform 40 oil changes between 10 am and 12pm. treating this as a random sample, what mean oil change time would there be a 10% chance of being at or below?
  8. statistics

    A study of the amount of time it takes a mechanic to rebuild the transmission for a 1992 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.77 hours. Assume that a random sample of 40 mechanics is selected …
  9. Math

    A study of the amount of time it takes a mechanic to rebuild the transmission for a 1992 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.77 hours. Assume that a random sample of 40 mechanics is selected …
  10. Math ---HELP!!!!!

    A study of the amount of time it takes a mechanic to rebuild the transmission for a 1992 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.77 hours. Assume that a random sample of 40 mechanics is selected …

More Similar Questions