Find the standard deviation of the sample data set. 127 135 128 131 133 127 122 A. 4.4 B. 4.0 C. 19.0 D. 2.0
Mathematics · Middle School · Tue Nov 03 2020
Answered on
Formula :
Standard deviation = √variance
We have,
127 135 128 131 133 127 122
Now, Mean = (127 + 135 + 128 + 131 + 133 + 127 + 122)/7
= 129
Now, difference of mean and each value :
127 - 129 = -2
135 - 129 = 6
128 - 129 = -1
131 - 129 = 2
133 - 129 = 4
127 - 129 = -2
122 - 129 = -7
Variance = ( -2² + 6² -1² + 2² + 4² -2² -7²)/7
= 114/7
= 16.28
Now, standard deviation = √16.28
= 4.034
Hence, option (B) is correct.