Posted by **Anonymous** on Tuesday, March 20, 2012 at 8:07pm.

The scores on a national achievement test are normally distributed with a mean of 50 and a standard deviation of 10. Out of a group of 200 students, how many would you expect to score more than 70?

- statistics -
**MathMate**, Tuesday, March 20, 2012 at 8:16pm
μ=50, σ=10;

For score 70, convert to standardized value

z=(x-μ)/σ=(70-50)/10=2

P(x>70)=P(z>2)

Look up standard normal distribution table to get

P(z<=2)=0.9772, so

P(x>70)=P(z>2)=1-0.9772=0.0228

or the average number of students with score of 70 or more

= P(x>70)*200=4.56 = 5 approx.

## Answer this Question

## Related Questions

- statistics - Suppose that the population standard deviation (ó) for a normally ...
- statistics - Ram earned a score of 940 on a national achievement test. The mean ...
- Statistics - Suppose you administered an anxiety test to a large sample of ...
- statistics - Suppose you administered an anxiety test to a large sample of ...
- statistics - In a psychology class of 100 students, test scores are normally ...
- Analytical Skills - If your score on a statistics exam was 76 and the professor ...
- statistics - The scores for math test #3 were normally distributed. If 15 ...
- Statistics - The scores for math test #3 were normally distributed. If 15 ...
- College of education ekiadolor Benin - The scores of an achievement test given ...
- Word Problem - A math teacher gives two different tests to measure students' ...

More Related Questions