Question

PLEASE someone help me!! I want to cry...T.T

Answer 1

Post your questions...?

Answer 2

Last semester the overall score of College Algebra classes was 72.5 with a standard deviation of 7.5 and the scores were distribuited normally. I want to set up a College algebra grade scale such that the top 5% of scores would earn A, scores below top 5% and above the bottom 75% earn a B, scores top 25% and above the bottom 25% earn a C, scores below top 75% and above the bottom 5% earn a D, and bottom 5% earn an F. Wwhat are the numerical limits for each letter grade?

Answer 3

Reference to a standard normal distribution table gives the following values of z corresponding to the stated values of cumulative probability as percentages:
5% : z = -1.645
25% : z = -0.674
75% : z = 0.674
95% : z = 1.645
Remembering that z is in terms of the number of standard deviations from the mean, the scores relating to the above percentages are found as follows:
5% : 72.5 - (1.645 * 7.5) = 60.16
25% : 72.5 - (0.674 * 7.5) = 67.45
75% : 72.5 + (0.645 * 7.5) = 77.34
95% : 72.5 + (1.645 * 7.5) = 84.84
You can now find the numerical limits for each letter grade.