Finding Standard Deviation from a Frequency Distribution. In Exercises,find the standard deviation of sample data summarized in a frequency distribution table by using the formula befaw, where x represents the class midpoint, f represents the class frequency, and n represents the total number ofsamph values. Aho, compare the computed standard deviations to these standard deviations obtained by using Formula 34 with the original list of data values: 9.0 years.
Age of Best Actor When Oscar Was 

Won 
Frequency 
20–29 
1 
30–39 
26 
40–49 
35 
50–59 
13 
60–69 
6 
70–79 
1 
Problem 38BSC
Answer:
Step1 of 3:
We have standard deviation for frequency distribution
s =
Where,
x represents the class midpoint,
f represents the class frequency, and
n represents the total number of sample values.
Age of Best Actor When Oscar Was  Frequency 
20–29  1 
30–39  26 
40–49  35 
50–59  13 
60–69  6 
70–79  1 
Step2 of 3:
We need to find the standard deviation of sample data summarized in a frequency distribution table by using the formula below,also, compare the computed standard deviations to these standard deviations obtained by using Formula 34 with the original list of data values. 11.1 years.
Step3 of 3:
Consider,
Age of Best Actor When Oscar Was  Frequency (f)  Mid point(x)  x2  fx2  fx 
20–29  1  24.5  600.25  600.25  24.5 
30–39  26  =34.5  1190.25  30946.5  897 
40–49  35  44.5  1980.25  69308.75  1557.5 
50–59  13 