# statistics

posted by .

1. A test has a mean of 50, standard deviation of 10.
A. What scores separate the middle 25% from the rest
b. What proportion would be expected to score between 45 and 55
c. What proportion would be expected to score 68 and above

• statistics -

Z = (score-mean)/SD

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions and their related Z scores.

A. Find the Z score with .125 between score and mean. Insert ±Z value in the above equation and solve for the scores.

B and C. Solve for Z scores and use the table.

## Similar Questions

1. ### Statistics

Students were given an exam with 300 multiple-choice questions. The distribution of the scores was normal and mean was 195 with a standard deviation of 30. What were the scores of the students who were within one standard deviation …
2. ### statistics probability

Alice earned a score of 940 on an IQ test.The mean test score was 850 with a standard deviation of 100.(Assume that test scores are normally distributed). Q1a).What proportion of students had a higher score than alice?
3. ### statistics

The scores on a personality test are normally distributed with a mean of 250 and a standard deviation of 30. What proportion of people taking the test can be expected to score above 229?
4. ### Statistics

A distribution of 800 test scores in a biology course was approximately normally distributed with a mean of 35 and a standard deviation of 6. Calculate the proportion of scores falling between 20 and 40
5. ### Statistics Math Help

A distribution of 800 test scores in a biology course was approximately normally distributed with a mean of 35 and a standard deviation of 6. Calculate the proportion of scores falling between 20 and 40
6. ### statistics

4. A large company insists that all job applicants who are invited for an interview take a psychometric test. The results of these tests follow a normal distribution with a mean of 61% and a standard deviation of 7.2%. a) What proportion …
7. ### statistics

Ram earned a score of 940 on a national achievement test. The mean test score was 850 with a standard deviation of 100.what proportion of student had a higher score than Ram?
8. ### Statistics

Bob takes an online IQ test and finds that his IQ according to the test is 134. Assuming that the mean IQ is 100, the standard deviation is 15, and the distribution of IQ scores is normal, what proportion of the poulation would score …
9. ### statistics

Suppose that the scores on a reading ability test are normally distributed with a mean of and a standard deviation of . What proportion of individuals score more than points on this test
10. ### stats

scores on the SAT critical reading test in 2013 follow a normal distribution with a mean score of 496 and a standard deviation of 115. what proportion of scores are higher thzn 530?

More Similar Questions