The district uses a standardized reading test to assess a student’s reading level and that scores on this test are normally distributed with a mean of 250 and a standard deviation of 20.

Question

A public school district has been given federal development funds to establish remedial reading classes for the students in grades 1 through 3. The district uses a standardized reading test to assess a student’s reading level and that scores on this test are normally distributed with a mean of 250 and a standard deviation of 20. To be eligible for these classes a pupil must score in the bottom 10% of all district wide students who took the test. What is the maximum score that a student can receive and still be eligible for the remedial reading class?

Answer 1

A calculator program that returns proportions of area under the Standard Normal Curve

for values of z [equal to (Test Score - 250) divided by 20] gives:

9.68004846% for score of 224;

10.56497737% for score of 225.

Then the highest whole-number score that will keep one in the bottom 10% of scores for those tested will be 224.