# Standard Deviation homework

1. Feb 18, 2004

### Ezekiel20

To anybody that can offer a hand.

<x>=5, Standard Deviation = 2, median Mx=4.5, Quartile1=4, Quartile 2=6, xmin=0, xmax=9.

After a linear tranform: y= -2x+1. What are <y>, Standard deviation y, median y, Q1y, Q2y, Ymin, Ymax.

I was given this equation for homework and I am totally lost.

2. Feb 18, 2004

### mathman

Except for the standard deviation, all the items you want can be botained by simply applying the linear transformation to an x quantity to get the corresponding y quantity. For example <y>=-2<x>+1. To get the standard deviation, you multiply by the absolute value of the multiplicative constant, therefore y standard deviation is 4.

3. Feb 19, 2004

### matt grime

mean: $$E:=\sum_nx_i/N$$ where N is the number of measurements (or whatever) transform by ax+b $$\sum_n(ax_i+b)/N=a\sum_nx_i/N +\sum_nb/N = b+ a\sum_nx_i/N = b+aE$$