A certain list of 100 data has mean of 6 and S.D = d and d = +ve ..Which of the following pairs of data when added to the list must result in a list of 102 data with s.d < d.
-6 and 0
0 and 0
0 and 6
0 and 12
6 and 6
oa 5
i got this question right but i want to know if the formula or the method that i applied is correct or not ..somebody please explain me this concept
mean median concept explain please :)
This topic has expert replies
- cans
- Legendary Member
- Posts: 1309
- Joined: Mon Apr 04, 2011 5:34 am
- Location: India
- Thanked: 310 times
- Followed by:123 members
- GMAT Score:750
mean=6
s.d. = d
n=100 (no. of elements)
to decrease the s.d. of new set, the elements must be added close to the mean)
e)6&6 will keep mean same as 6 and also thus standard deviation will decrease.
IMO E
s.d. = d
n=100 (no. of elements)
to decrease the s.d. of new set, the elements must be added close to the mean)
e)6&6 will keep mean same as 6 and also thus standard deviation will decrease.
IMO E
If my post helped you- let me know by pushing the thanks button
Contact me about long distance tutoring!
[email protected]
Cans!!
Contact me about long distance tutoring!
[email protected]
Cans!!
-
- Legendary Member
- Posts: 1085
- Joined: Fri Apr 15, 2011 2:33 pm
- Thanked: 158 times
- Followed by:21 members
attached is the formula of s.d.
n can be 100 or 102
as you see the '0' effect on numerator of s.d. is achieved by the pair 6,6
and the n is increasing, n=102. Hence s.d. will be less than d, as in the numerator of s.d. all numbers are squared and may be greater than d.
n can be 100 or 102
as you see the '0' effect on numerator of s.d. is achieved by the pair 6,6
and the n is increasing, n=102. Hence s.d. will be less than d, as in the numerator of s.d. all numbers are squared and may be greater than d.
- Attachments
-
Success doesn't come overnight!