s.d

[crackinggmat]

Is the standard deviation of the salaries of Company Y's employees greater than the standard deviation of the salaries of Company Z's employees?

(1) The average (arithmetic mean) salary of Company Y's employees is greater than the average salary of Company Z's employees.
(2) The median salary of Company Y's employees is greater than the median salary of Company Z's employees.


answer is A but how????

[sanju09]

Is the standard deviation of the salaries of Company Y's employees greater than the standard deviation of the salaries of Company Z's employees?

(1) The average (arithmetic mean) salary of Company Y's employees is greater than the average salary of Company Z's employees.
(2) The median salary of Company Y's employees is greater than the median salary of Company Z's employees.


answer is A but how????

(1) Since, standard deviation refers to the square root of the mean squared deviation of a quantity from a given datum, hence for the data having comparably greater mean, our first wisecrack might be to say that the employees at Company Y are getting better salaries.

But a bigger standard deviation for one company tells us that there are relatively more employees in the company getting salaries toward one extreme or the other.

(2) Since, median plays no role in assigning an SD of a quantity from a given datum, this is insufficient

[Rezinka]

Raising an old post,
Can someone tell me how is A the answer?

Suppose,
Set A : 7,8,9,10,11

Set B : 1,3,5,7,9

Mean for Set A > Set B, but SD for B>A

shouldn't the answer to the question above be E?

[Geva@EconomistGMAT]

Raising an old post,
Can someone tell me how is A the answer?

Suppose,
Set A : 7,8,9,10,11

Set B : 1,3,5,7,9

Mean for Set A > Set B, but SD for B>A

shouldn't the answer to the question above be E?

I agree - Answer should be E.
Your example does present the counter example to give a "no" answer for both statements, and using the reverse formation:

Set A: 7, 9, 11, 13, 15,

set B: 1,2,3,4,5,

will show the opposite result of "yes".
In qualitative, rather than quantitative, SD is a measure of the dispersal of the terms in each set around their respective average. Neither the average nor the median tell us much about how the terms are dispersed around their average - either close together or far apart.