# Standard Normal Distribution

• March 1st 2011, 12:13 PM
Laydieofsorrows
Standard Normal Distribution
Let Z1, Z2, ... Z7 be a random sample from the standard normal distribution N(0, 1). Let W = Z1 ^2, Z2 ^2, ... Z7 . Find P(1.69 < W < 14.07.

I have no idea where to begin with this one.

Thanks
• March 1st 2011, 05:01 PM
matheagle
I would guess that you mean W is the sum of the squares of the Z's which makes it a chi-square with 7 degress of freedom.
Otherwise W is a vector and you're missing 6 other parts of the question.
So go to a $\chi^2_7$ table and look up those numbers OR use....http://www.statsoft.com/textbook/dis...on-tables/#chi
from that the answer is .975-.05.