Posted by **mary** on Monday, February 1, 2010 at 8:50pm.

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 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.

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. It is simple what happens when you subtract 21 from 21.

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?

- psychology (statistics) -
**PsyDAG**, Tuesday, February 2, 2010 at 9:21am
First one is right, Z = 1.33.

When you subtract **12** from 21, you get a negative number.

Lastly, Z = 0, since there is no deviation from the mean. It is the mean value.

I hope this helps.

## Answer this Question

## Related Questions

- statistics - Eric has computed that it takes an average (mean) of 17 minutes ...
- psy - Please help, very lost Eric has computed that it takes an average (mean) ...
- psy - Eric has computed that it takes an average (mean) of 17 minutes with a ...
- Statistics - Eric has computed that it takes an average (mean) of 17 minutes ...
- Math - Ms. Peters drove from her home to the park at an average speed of 30 ...
- Mathamatics - A walk up a hill starts at a car park on the 100m contour and ...
- statistics - Times for a surgical procedure are normally distributed. There are ...
- 6th grade math - Mya works on Saturdays and then attends a study group. She ...
- statistics - John drives to work each morning and the trip takes an average of...
- Statistics - John drives to work each morning and the trip takes an average of m...

More Related Questions