# Statistics

posted by Will

I know don't know if this right P(X)<115)= 12.1 (115-mean) how do I get the mean or is there a formula that can help me solve this?

A population of line voltages has a standard deviation of 1.20 volts. What value would the mean line voltage have to be so that 12.1% of the line voltages fell below 115V?

1. PsyDAG

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (.121) and its Z score. Z score = -1.27 is standard deviations below the mean.

115 + 1.27(1.2) = mean

## Similar Questions

1. ### statistics

The Survey of Study Habits and Attitudes (SSHA) is a psychological test that measures students' study habits and attitudes toward school. Scores range from 0 to 200. The mean score for college students is about 115.8, and the standard …
2. ### statistics

The Survey of Study Habits and Attitudes (SSHA) is a psychological test that measures students' study habits and attitudes toward school. Scores range from 0 to 200. The mean score for college students is about 115.8, and the standard …
3. ### statistics

Assume that a population is normally distributed with a mean of 100 and a standard deviation of 15. Would it be unusual for the mean of a sample of 3 to be 115 or more?
4. ### statistics

Assume that a population is normally distributed with a mean of 100 and a standard deviation of 15. Would it be unusual for the mean of a sample of 20 to be 115 or more?
5. ### statistics

Assume that a population is normally distributed with a mean of 100 and a standard deviation of 15. Would it be unusual for the mean of a sample of 3 to be 115 or more?
6. ### statistics

Assume that a population is normally distributed with a mean of 100 and a standard deviation of 15. Would it be unusual for the mean of a sample of 3 to be 115 or more?
7. ### Statistics

Assume that a population is normally distributed with a mean of 100 and a standard deviation of 15. Would it be unusual for the mean of a sample of 3 to be 115 or more?
8. ### Statistics

A student wants to test her hypothesis she gives each of her students an IO test. She finds that the average IQ score is 115 and the standard deviation for the class is 30. There are 22 students in the class. She also knows that the …
9. ### Quality Control

How need help with this one. This is what I know P(X)<115)= 12.1 (115-mean) how do I get the mean or is their a formula that can help me solve this?
10. ### Statistics

Use the following information to answer the following questions. IQ is measured with scores that range from 0-200. Thea mean is 100 and the standard deviation in the population is 15. What is the probability that a randomly chosen …

More Similar Questions