If d is the standard deviation x, y, and z, what is the standard deviation of x + 5, y + 5, z + 5?

This topic has expert replies
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 8086
Joined: Sat Apr 25, 2015 10:56 am
Location: Los Angeles, CA
Thanked: 43 times
Followed by:29 members
BTGmoderatorLU wrote:
Sun Dec 27, 2020 8:20 am
Source: GMAT Prep

If d is the standard deviation x, y, and z, what is the standard deviation of x + 5, y + 5, z + 5?

A. d
B. 3d
C. 15d
D. d + 5
E. d + 15

The OA is A
Solution:

In a data set, if every number is increased (or decreased) by the same amount, the standard deviation of the data set will not be affected. That is, the new standard deviation is still equal to the original standard deviation. Here we see that each data value is increased by the same amount (5 in this case); therefore, the standard deviation will still be d.

Answer: A

Scott Woodbury-Stewart
Founder and CEO
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

ImageImage