Question 1140379
The formula you want is 
z>(x bar-mean)/sd/sqrt(n), which becomes (x bar-mean)*sqrt(n)/sd
variance is 16, sd=4
so z> (13.6-14)*sqrt(40)/4

I would use z and not t here, because the designer claims a mean of 14 and sd 4, and the sample's sd is not considered here.