I need help with this question

#1
Hello,

could you help me solving this? Thanks a lot


What is the expected value and standard deviation of T?

T=a·b·ΔT
a=10+0.1ΔT (ppm/ºC)
b=N(6,0.2) m
ΔT=N(15,4) ºC
 
#3
I know,

I know the rule:
If x & y are independent:
E(xy)=E(x)·E(y)
σxy^2= μx^2·σy^2 + μy^2·σx^2 + σx^2·σy^2

Here we have 3 variables, and "a" depends on ΔT

I did this:
Total mean = (10+0.1·15)·10^-6 · 6 · 15
but I think it is totally incorrect

"Total σ" seems to be even more difficult