In a hearing test,subjects estimate the loudness (in decibels)of sound,and the results are (mean = 70): 68,67,70,71,68,75,68,62,80,73,68 What is the standard deviation?
A)18
B)4.73
C)22.40
D)324
E)6.76

Question

Quizplus · Accepted Answer

To find the standard deviation, we need to use the formula:

SD = sqrt [(Σ(x-μ)²)/N]

where Σ denotes sum, x denotes the individual scores, μ denotes the mean, and N denotes the sample size.

Plugging in the values, we get:

SD = sqrt [{(68-70)² + (67-70)² + (70-70)² + (71-70)² + (68-70)² + (75-70)² + (68-70)² + (62-70)² + (80-70)² + (73-70)² + (68-70)²} / 11]

SD = sqrt [(4+9+0+1+4+25+4+64+100+9+4) / 11]

SD = sqrt [224 / 11]

SD = 4.73 (approximately)

Therefore, the standard deviation is 4.73. Option B is correct.

In a Hearing Test,subjects Estimate the Loudness (In Decibels)of Sound,and