Rewrite this to:=1-P(1375-1400/100 < Z < 1500-1400/100)
=1-P([1375-1400]/100 < Z < [1500-1400]/100)
You know what you mean by the original, but that is not what the notation says.
Rewrite this to:=1-P(Z<1) - P(Z<-.25)
=1-[P(Z<-1) - P(Z<-.25)]
Again, you know what you mean by the original, but that is not what the notation says.
Also, you are missing the negative sign in the first probability. Your clue should have been that it was greater than 1/2. That is quite unlikely for a Normal Distribution and a value below the mean. Since this was the wrong value, they are now int he wrong order. You should have [P(Z<-0.25) - P(Z<-1.00)]
Is that supposed to be P(Z<-0.25)? You had better calculate that again. You simply must keep in mind some relative estimates. Keep the empirical rule in mind. Z = -0.25 is just a little below the mean. For P(Z < -0.25), you should get a value quite close to 1/2. For P(Z < -1), you should get a value in the neighborhood of 0.50 - 0.34 = 0.16.0062
Good work. A little cleaner and a little more careful and you'll have it!!