probability

suppose that the times taken to complete an online test are normally distributed with a mean of 45 minutes and a standard deviation of 12 minutes. find the probability
a. that for a randomly selected test, the time taken was more than 1 hour.

b. that the mean number of minutes taken by a random sample of 24 tests is less than 50 minutes

asked by Jennifer
  1. a. Z = (score-mean)/SD

    b. Z = (score-mean)/SEm

    SEm = SD/√n

    For each, find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.

    posted by PsyDAG

Respond to this Question

First Name

Your Answer

Similar Questions

  1. statistics

    The times taken to complete a statistics test by all students are normally distributed with a mean of 120 minutes and a standard deviation of 12 minutes. Find the probability that the mean time taken to complete this test by a
  2. statistics

    The times taken to complete a statistics test by all students are normally distributed with a mean of 120 minutes and a standard deviation of 12 minutes. Find the probability that the mean time taken to complete this test by a
  3. statistics

    a statistics instructor collected data on the time it takes the students to complete a test. the test taking time is uniformly distributed within a range of 35 minutes to 55 minutes. determine the standard deviation, what is the
  4. 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
  5. math

    the courier service company has found that their time of parcels to client is normally distributed with a mean of 45 minutes and a standard deviation of 8 minutes. the probability that a randomly selected parcel will take less
  6. math

    The time required to finish a test in normally distributed with a mean of 80 minutes and a standard deviation of 15 minutes. What is the probability that a student chosen at random will finish the test in more than 110 minutes?
  7. Math

    The time required to finish a test in normally distributed with a mean of 40 minutes and a standard deviation of 8 minutes. What is the probability that a student chosen at random will finish the test between 24 and 48 minutes?
  8. statistics

    Suppose the amount of time it takes for statistics students to complete their midterm is normally distributed with a mean of 85.70 minutes and a standard deviation of 22.55 minutes. If 10 students are randomly selected, what is
  9. math

    Test scores on a university admissions test are normally distributed, with a mean of 500 and a standard deviation of 100. a. What is the probability that a randomly selected applicant scores between 425 and 575? b. What is the
  10. Statistics

    The average time a visitor spends at the Renzie Park Art Exhibit is 62 minutes. The standard deviation is 12 minutes. If a visitor is selected at random, find the probability that he or she will spend: A)At least 82 minutes at the

More Similar Questions