Date: Tue, 23 Sep 1997 15:28:53 -0400
From: Alex Bogomolny
Dear Susan:
You have
E[(X-1)^2]=10 and
E[(X-2)^2]=6
This means that
E[X^2 - 2X + 1] = 10, and
E[X^2 - 4X + 4] = 6
Subtract second from the first:
E[2X - 3] = 4, or
2E[X] - 3 = 4. Hence E[X] = 7/2.
Would you be able to find the variance now?
Regards
Alexander Bogomolny
71491818