math

posted by .

In a random sample of 1,000 exams, the average score was 500 points with a standard deviation of 80 points. Find the interval about the sample mean such that the probability is 0.90 that the mean number lies within the interval.

  • math -

    90% = mean ± 1.645 SEm

    SEm = SD/√n

    I'll let you do the calculations.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. statistics

    The scores of students on the ACT college entrance examination in a recent year had a normal distribution with a mean of 18.6 and a standard deviation of 5.9. A simple random sample of 50 students who took the exam is selected for …
  2. statistics

    what are the mean and standard deviation of a sampling distribution consisting of samples of size 16?
  3. Math

    In a random sample of 30 tires of the same type, it is found that the average life span is 36,200 miles with a standard deviation of 3800 miles. Find the interval about the sample mean such that the probability is 0.77 that the mean …
  4. Statistics

    1. The scores of students on the ACT college entrance examination in a recent year had a normal distribution with a mean of 18.6 and a standard deviation of 5.9. A simple random sample of 60 students who took the exam is selected for …
  5. Statistics

    In an essay of 250-500 words, thoroughly address the following items and respond to the related questions: 1.Define the term standard deviation. Why is it important to know the standard deviation for a given sample?
  6. statistics

    The College Board reported the following mean scores for the three parts of the Scholastic Aptitude Test (SAT) (The World Almanac, 2009): Assume that the population standard deviation on each part of the test is = 100. a. What is the …
  7. statistics

    The College Board reported the following mean scores for the three parts of the Scholastic Aptitude Test (SAT) (The World Almanac, 2009): Assume that the population standard deviation on each part of the test is = 100. a. What is the …
  8. Statistics

    The College Board reported the following mean scores for the three parts of the Scholastic Aptitude Test (SAT) (The World Almanac, 2009): Assume that the population standard deviation on each part of the test is = 100. a. What is the …
  9. Math

    The College Board reported the following mean scores for the three parts of the Scholastic Aptitude Test (SAT) (The World Almanac, 2009): Assume that the population standard deviation on each part of the test is = 100. a. What is the …
  10. math

    The winning team's score in 13 high school basketball games was recorded. If the sample mean is 54.3 points and the sample standard deviation is 11.0 points, find the 98% confidence interval of the true mean.

More Similar Questions