Find the standard​ deviation, s, of sample data summarized in the frequency distribution table given below.

Question

Find the standard​ deviation, s, of sample data summarized in the frequency distribution table given below.

Interval

30​-39

40​-49

50​-59

60​-69

70​-79

80​-89

Frequency

3

23

39

20

10

4

1. Standard deviation= _______ ​(Round to one decimal place as​ needed.)
2. The standard deviation obtained from the original list of data values is 9.0. How does this compare to the value you computed from the frequency​ distribution? Consider a difference of​ 20% between two values of a standard deviation to be significant.

A. The computed value is significantly greater than the given value.

B.The computed value is significantly less than the given value.

C. The computed value is not significantly different from the given value.

Answer 1

Formulas to compute standard deviation:

mean = [sum of (f * x(i))]/sum(f), where x(i) is the midpoint of each class

variance = [sum of (f * (x(i) - mu)**2)]/(sum(f) - 1)

standard deviation = square root of variance