Practice problems…

Percentages, # correct/ total # of items

Z-scores, (observed score – mean)/ standard deviation

T-scores, (Z*10) + 50

Percentile, [c*f* + .5 (*f *i)]/N

Dr. Day’s class (N = 40) just took a History & Systems exam with 50 items. The mean score was 35 and the SD was 5.

Calculate percentage scores, Z-scores, T-scores, and Percentiles for the following students.

Raw Score # of persons with the same score # of persons scoring below their score

Darius 25 1 2

Kay 35 4 16

Scroll down for the answers…

Percentage Z T Percentile

Darius 50 -2 30 .08 (7.50%)

Kay 70 0 50 .46 (46.25%)