Stockmoose16 wrote:Can someone please explain this question?
The table shows the number of calls received by each of five operators during each of 4 one-hour periods. For which operator was the standard deviation of the numbers of calls received during these 4 periods the least?
Operator A: 3, 7, 7, 3
Operator B: 4, 5, 5, 6
Operator C: 8, 2, 5, 5
Operator D: 6, 4, 4, 6
Operator E: 3, 4, 5, 8
OA is B
SM16,
From Wikipedia, the free encyclopedia
In probability and statistics, the standard deviation is a measure of the dispersion of a collection of numbers. It can apply to a probability distribution, a random variable, a population or a data set. The standard deviation is usually denoted with the letter σ (lowercase sigma). It is defined as the root-mean-square (RMS) deviation of the values from their mean, or as the square root of the variance. Formulated by Galton in the late 1860s,[1] the standard deviation remains the most common measure of statistical dispersion, measuring how widely spread the values in a data set are. If many data points are close to the mean, then the standard deviation is small; if many data points are far from the mean, then the standard deviation is large. If all data values are equal, then the standard deviation is zero. A useful property of standard deviation is that, unlike variance, it is expressed in the same units as the data.
Well - the more the terms are closer to the median , the smaller the SD
AV = Average ( by the way to make the calculation easy, the author designed the question so they all have the same average )
DIFF = # = AV
Operator A: 3, 7, 7, 3 AV :5 DIFF 2 2 2 2
Operator B: 4, 5, 5, 6 AV :5 DIFF 1 0 0 1
Operator C: 8, 2, 5, 5 AV :5 DIFF 3 3 0 0
Operator D: 6, 4, 4, 6 AV :5 DIFF 1 1 1 1
Operator E: 3, 4, 5, 8 AV :5 DIFF 2 1 0 3
