standard deviation question (1 Viewer)

[Greninja340]

Say they give us the mean and sd of a certain data set, and then they tell us another data score is added, how do we determine if the sd is gonna increase or decrease.
E.g. Mean=70 sd=7, a score of 62 is added to the data set, what happens to the sd and the mean

 

[IDK and IDC]

from what you have said, and my learning from past paper questions, this is what i would do
so ur data in the zscore formula would look like
62= x-70 / 7

i would just rearrange the formula to ((z-score)x(sd)) + mean)
so now it will look like ((62) x (7)) +70
and that = 504
i might be wrong so idk

 

[Jerryclover]

from what you have said, and my learning from past paper questions, this is what i would do
so ur data in the zscore formula would look like
62= x-70 / 7

i would just rearrange the formula to ((z-score)x(sd)) + mean)
so now it will look like ((62) x (7)) +70
and that = 504
i might be wrong so idk

I think you're overcomplicating this. If standard deviation is 7 and someone scored 8 points less than 70, then standard deviation would increase as 8>7. And obviously the mean will decrease aswell since 62 is less than 70.