Chi-Squared Problems

1. For the following set of scores, find the value of ach expression:
X
6
-1
0
-3
-2

a. ∑X
b. ∑X²
c. ∑(x+3)

2. The following frequency distributionpresents a set of exam scores for class of n=20 students.

X
6
-1
0
-3
-2
X f cf c%
90-99 4 20 100
80-89 7 16 80
70-79 4 9 45
60-69 3 5 25
50-59 2 2 10

A. find the 30th percentile
B. find the 88 percentile
C. what is the percentilerank for x=77
D. what is the percentile rank for x=90

Please see the attached file.

Qk = L+w/fk*(kn-cfb)
Where
Qk = the kth percentile
L = lower limit of the class interval that includes the kth percentile
n = total frequency
cfb = …

Two problems are solved dealing with chi-squared distributions and percentile ranks.