Exhibit 3-4
The following is the frequency distribution for the speeds of a sample of automobiles traveling on an interstate highway.
-Refer to Exhibit 3-4. The standard deviation is
A)6.969
B)7.071
C)48.570
D)50.000

Question

Exhibit 3-4
The following is the frequency distribution for the speeds of a sample of automobiles traveling on an interstate highway. 
-Refer to Exhibit 3-4. The standard deviation is
A)6.969 
B)7.071 
C)48.570 
D)50.000

Quizplus · Accepted Answer

The standard deviation can be found by taking the square root of the variance. The variance can be calculated using the formula: variance = [(Σx^2)/n] - [(Σx/n)^2]. Using the given frequency distribution, we can calculate the mean speed as (2100/200) = 10.5. Then, using the formula for variance, we get variance = [(32200/200) - (10.5^2)] = 49.455. Taking the square root of this gives us the standard deviation of approximately 7.071. Therefore, the best choice is B.

Exhibit 3-4 the Following Is the Frequency Distribution for the Speeds of Speeds