Question

Find the standard deviation (rounded to the nearest unit) for the data indicated.

Test Score Frequency
90 2
80 5
70 9
60 6
50 4
40 1
30 2
0 5

Answer 1

Just pretend that you have:
90,90,80,80,80,80,80, ... ,30,30,0,0,0,0,0
add up the frequencies to find out how many entries you have, that would be 34
mean = sum of all the entries/34

use the method you learned to find the SD of these 34 entries.