I like to think of the - or under as the less likely to happen like a cat beating up a bear u don’t want to put your money on the cat so everyone puts there money on the bear making the bear the over and the cat the under
For T = 89.5 degrees C: E(t) = 1100(90 - 89.5) + 520(90 - 89.5)^2= 1100(0.5) + 520(0.5)^2= 550 + 130= 680 m For T = 90 degrees C: E(t) = 1100(90 - 90) + 520(90 - 90)^2= 0 + 0= 0 m (meaning that boiling point is 90 degrees C at ground level)