Your answer will be 13. :-)
Let's write the parametric line
(x,y,z) = (0,2,8) + t(5,-1,4)
(5,-1,4) is called the direction vector of the line. It's normal to the plane
5x - y + 4z = constant
We get the constant by substituting the point (3,0,7),
5x - y +4z = 5(3) - 0 + 4(7) = 43
5x - y +4z = 43
The mean is just the arithmetic average:
(103+99+90+86+105+96+x)/7=95
(579+x)/7=95
579+x=665
x=86
I don't see how this is math related but let me ask why do you want to? Best friends don't normally leave when things get tough. I mean I do understand. And I will tell you my opinion if you truly want it as well. Jw.
