Statistics

posted by .

Eric has computed that it takes an average (mean) of 17 minutes with a standard deviation of 3 minutes to drive from home, park the car, and walk to his job. One day it took Eric 21 minutes to get to work. You would use the formula for transforming a raw score in a sample into a z-score to determine how many standard deviations the raw score represents. Since his "score" is 21, you would subtract the mean of 17 from 21 and divide that result (4) by the standard deviation of 3. The z-score of 1.33 tells you that Eric’s time to get to work is 1.33 standard deviations from the mean

Questions
Is the z value positive or negative? Explain why it should be positive or negative.
Another day, it took Eric only 12 minutes to get to work. Using the same formula, determine the z value. Is it positive or negative? Explain why it should be positive or negative.
On a different day, it took Eric 17 minutes to get from home to work. What is the z value? Why should you expect this result even before you did the calculation?
Based on your study of z-scores, explain the three uses of z-scores. How might they each relate to Eric's trip between home and work?
What is the relationship between z-scores and the standard normal curve?

  • Statistics -

    Since Z = (score-mean)/SD, scores below the mean will have a negative value, and those above the mean will have a positive value.

    Since you did the calculation of the first Z score, you should be able to do the same for the other Z scores.

    For a normal distribution, the Z scores express raw scores in terms of SDs from the mean. The proportions cut off are the same for any normal distribution. Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions related to your Z scores.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. 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 …
  2. psy

    Eric has computed that it takes an average (mean) of 17 minutes with a standard deviation of 3 minutes to drive from home, park the car, and walk to his job. One day it took Eric 21 minutes to get to work. You would use the formula …
  3. psy

    Please help, very lost Eric has computed that it takes an average (mean) of 17 minutes with a standard deviation of 3 minutes to drive from home, park the car, and walk to his job. One day it took Eric 21 minutes to get to work. You …
  4. psycholgy

    Please help, very lost Eric has computed that it takes an average (mean) of 17 minutes with a standard deviation of 3 minutes to drive from home, park the car, and walk to his job. One day it took Eric 21 minutes to get to work. You …
  5. statistics

    Eric has computed that it takes an average (mean) of 17 minutes with a standard deviation of 3 minutes to drive from home, park the car, and walk to his job. One day it took Eric 21 minutes to get to work. You would use the formula …
  6. statistics

    John drives to work each morning and the trip takes an average of µ = 38 minutes. The distribution of driving times is approximately normal with a standard deviation of ó = 5 minutes. For a randomly selected morning, what is the …
  7. statistics

    The time required by workers to complete an assembly job has a mean of 50 minutes and a standard deviation of 8 minutes. To spot check the workers' progress on a particular day, their supervisor intends to record the times 60 workers …
  8. statistics

    Times for a surgical procedure are normally distributed. There are two methods. Method A has a mean of 28 Minutes and a standard deviation of 4 minutes, while B has a mean of 32 minutes and a standard deviation of 2 minutes. a)which …
  9. Dine

    Men spend an average of 29 minutes per day on weekends and holidays exercising and playing sports. They spend an average of 23 minutes per day reading. A random sample of 25 men resulted in a mean of 35 minutes exercising with a standard …
  10. Statistics

    John drives to work each morning and the trip takes an average of µ = 38 minutes. The distribution of driving times is approximately normal with a standard deviation of s = 5 minutes. For a randomly selected morning, what is the probability …

More Similar Questions