Math

Suppose that a New Jersey testing service has created a standardized test for assessing the reading and computing skills of 8th graders. The test consists of a reading part, which is structured to have a mean of 200 and a standard deviation of 50. It also has a mathematics part, which is structured to have a mean of 100 and a standard deviation of 20. Students take both parts of the test and are given a final score that is the sum of both parts together. What would be the standard deviation of the final student scores?

  1. 👍 0
  2. 👎 0
  3. 👁 115
asked by Hannah
  1. The mean combined score is 200 + 100 = 300 and the standard deviation of the combined score is sqrt[(50)^2 + (20)^2] = 53.9

    1. 👍 0
    2. 👎 0
    posted by drwls
  2. My previous answer assumed the two score distributions are uncorrelated. In actual practice, this may not be true, becasus students who score low in one test would tend to be the ones who score lowest in the other, and similarly for the highest. In other words, the two distributions are correlated. The actual standard deviation is probably somewhere between the sum of the separate standard deviations (70) and the "root sum of squares (RSS)" number of 53.9 previously mentioned.

    1. 👍 0
    2. 👎 0
    posted by drwls

Respond to this Question

First Name

Your Response

Similar Questions

  1. statistics

    Suppose you want to test the claim that mu is not equal to 3.5. Given a sample size of n = 31 and a level of significance of alpha = 0.10 when should you reject Ho? A) Reject Ho if the standardized test statistic is greater than

    asked by Brittany on June 21, 2011
  2. Math-Statistics

    Suppose you want to test the claim that mean is not equal 3.5. Given a sample size of n = 45 and a level of significance of a = 0.10, when should you reject H0 ? A) Reject H0 if the standardized test statistic is greater than 1.96

    asked by Jenny on December 12, 2009
  3. statistics

    A standardized third grade reading test, called the We Can Read Test, has a mean of 50 with a standard deviation of 10. A developmental psychologist conducts a study, where he assesses the reading ability of a random sample of 75

    asked by Lee on April 16, 2014
  4. statistics

    A standardized third grade reading test, called the We Can Read Test, has a mean of 50 with a standard deviation of 10. A developmental psychologist conducts a study, where he assesses the reading ability of a random sample of 75

    asked by Lee on April 15, 2014
  5. statistics

    A standardized third grade reading test, called the We Can Read Test, has a mean of 50 with a standard deviation of 10. A developmental psychologist conducts a study, where he assesses the reading ability of a random sample of 75

    asked by Lee on April 15, 2014
  6. referance

    can someone please find me a couple of websites, to practice for elementary standardized test It all depends on which standardized test you want to practice for. ITBS:

    asked by shivangi on March 12, 2007
  7. graduate statistics

    Does computer-assisted instruction help community college health students with reading difficulties to learn reading skills at a faster than normal rate? A researcher arranged for one of these students to have access to a set of

    asked by Anonymous on July 3, 2013
  8. statistics

    A standardized third grade reading test, called the We Can Read Test, has a mean of 50 with a standard deviation of 10. A developmental psychologist conducts a study, where he assesses the reading ability of a random sample of 75

    asked by Carrie on April 16, 2014
  9. FINITE MATH

    Applicants who wish to be admitted to a certain professional skill at a large university are required to take a screening test that was devised by an educational testing service. From the past results, the testing service has

    asked by MECCA on March 19, 2012
  10. statistics

    H0 is p = 0.45 and H1 is p ≠ 0.45. What type of test will be performed? A. Two-tail testing of a proportion B. One-tail testing of a proportion C. One-tail testing of a mean D. Two-tail testing of a mean ** I'm stuck

    asked by Jenn on February 23, 2018

More Similar Questions