Question

The mean test score for a class was 70 points, with a standard deviation of 15 points. If I now add 10 points to everyone's test score:

a) What is the mean test score for the class after I add the 10 points to each score?

b) What is the standard deviation of the test scores for the class after I add the 10 points to each score?

Answer 1

everything will stay the same because you're not influencing the number of scores that are present, you are just adding 10 to each value of the scores, if you know what i mean

Answer 2

Kind of sort of. But, we have to show our work on how we can to that conclusion.

Answer 3

ILL SOLVE IT OK

Answer 4

mean changed by 10

Answer 5

std by nothing

Answer 6

since

Answer 7

lets say
old mean = sum i from 1 to n of Xi /n

Answer 8

new mean = sum i from 1 to n of Xi+10 /n

Answer 9

= old mean +n*10/n =oldmean+10

Answer 10

so mean has changed by only 10

Answer 11

std = sqrt(sum(diff from mean^2)/n)

Answer 12

the diff from mean didnt change

Answer 13

let k be difference
xi-xbar

Answer 14

then xi+10 -(xbar+10) = k still

Answer 15

so you are summing same differences

Answer 16

That lost me even more.

Answer 17

lol wait

Answer 18

ill draw it after i finish eating

Answer 19

Ok.