# Math Help - Statistics:linear transformation

1. ## Statistics:linear transformation

Mean of 25 and standard deviation of 5. Rescale the test using linear transformation so that the mean is 100 and the standard deviation is 20...

I know I have to use xnew=a+bx. But at that point I'm stuck...and my book has no good examples!

2. $E(a+bX)=a+bE(X)$ and $V(a+bX)=b^2V(X)$

SO $100=a+b(25)$ and $400=b^2(25)$