Question

Scores on a test have a mean of 72.9 and 9 percent of the scores are...

Scores on a test have a mean of 72.9 and 9 percent of the scores are above 85. The scores have a distribution that is approximately normal. Find the standard deviation. Round your answer to the nearest tenth, if necessary.

Homework Answers

Answer #1

Solution :

mean = = 72.9

standard deviation = = ?

x = 85

Using standard normal table,

P(Z > z) = 9%

1 - P(Z < z) = 0.09

P(Z < z) = 1 - 0.09

P(Z < 1.34) = 0.91

z = 1.34

Using z-score formula,

x = z * +

= (x - ) / z = (85 - 72.9) / 1.34 = 9

standard deviation = 9

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
Scores on a test have a mean of 66 and Q3 is 80. The scores have...
Scores on a test have a mean of 66 and Q3 is 80. The scores have a distribution that is approximately normal. Find the standard deviation. Round your answer to the nearest tenth. Group of answer choices 10.5 20.9 18.7 9.4
The distribution of math test scores on a standardized test administered to Texas tenth-graders is approximately...
The distribution of math test scores on a standardized test administered to Texas tenth-graders is approximately Normal with a mean of 615 and a standard deviation of 46. Below what score do the worst 2.5% of the scores fall? (Hint: apply the 68-95-99.7 Rule.) Round your answer to the nearest integer.
The distribution of scores on a standardized aptitude test is approximately normal with a mean of...
The distribution of scores on a standardized aptitude test is approximately normal with a mean of 500 and a standard deviation of 95 What is the minimum score needed to be in the top 20% on this test? Carry your intermediate computations to at least four decimal places, and round your answer to the nearest integer.
Scores on a test have a mean of 71 and Q3 is 82. The scores have...
Scores on a test have a mean of 71 and Q3 is 82. The scores have a distribution that is approximately normal. Find P90
test scores in a MATH 1030 class is approximately normally distributed with mean 86 and standard...
test scores in a MATH 1030 class is approximately normally distributed with mean 86 and standard deviation 6. Round answers to the nearest tenth of a percent. a) What percentage of scores will be less than 88? % b) What percentage of scores will be more than 82? % c) What percentage of scores will be between 81 and 87? %
Scores on a certain intelligence test for children between ages 13 and 15 years are approximately...
Scores on a certain intelligence test for children between ages 13 and 15 years are approximately normally distributed with μ=96μ=96 and σ=15σ=15. (a) What proportion of children aged 13 to 15 years old have scores on this test above 88.5 ? (NOTE: Please enter your answer in decimal form. For example, 45.23% should be entered as 0.4523.) Answer:   (b) Enter the score which best approximates the lowest 8 percent of the distribution. Round your answer to the nearest tenth. Answer:...
1) Mathematics achievement test scores for 500 students were found to have a mean and a...
1) Mathematics achievement test scores for 500 students were found to have a mean and a variance equal to 590 and 4900, respectively. If the distribution of test scores was mound-shaped, approximately how many of the scores would fall into the interval 520 to 660? (Round your answer to the nearest whole number.) 2) Approximately how many scores would be expected to fall into the interval 450 to 730? (Round your answer to the nearest whole number.)
A humanities professor assigns letter grades on a test according to the following scheme. A: Top...
A humanities professor assigns letter grades on a test according to the following scheme. A: Top 12% of scores B: Scores below the top 12% and above the bottom 63% C: Scores below the top 37% and above the bottom 15% D: Scores below the top 85% and above the bottom 9% F: Bottom 9% of scores Scores on the test are normally distributed with a mean of 68 and a standard deviation of 7.6. Find the minimum score required...
Suppose ACT Reading scores are normally distributed with a mean of 21.5 and a standard deviation...
Suppose ACT Reading scores are normally distributed with a mean of 21.5 and a standard deviation of 6.3. A university plans to award scholarships to students whose scores are in the top 9%. What is the minimum score required for the scholarship? Round your answer to the nearest tenth, if necessary.
Scores on an aptitude test have been observed to be approximately normal with a mean of...
Scores on an aptitude test have been observed to be approximately normal with a mean of 76and a standard deviation of 5. If 1000 people took the test, how many would you expect to score above 80?
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT