Question

At higher elevations water boils at lower temperatures. The temperature at which water boils is called the boiling point of water. At sea level the boiling point of water is 100oC, while at 2 kilometers of elevation (about 6550 feet) the boiling point of water is 94oC. The function that gives the boiling point of water in oC, B
B
, at an elevation of x
x
kilometers is B(x)=100−3.5x
B(x)=100-3.5x
.

Determine the elevations at which the boiling point of water is between 84 oC and 96 oC. Give your answer accurate to 1 decimal place.

Answer 1

B(x) = 100 - 3.5x
84 = 100 - 3.5x
3.5x = 100 - 84 = 16
x = 16/3.5 = 4.6 kilometers

96 = 100 - 3.5x
3.5x = 100 - 96 = 4
x = 4/3.5 = 1.1 kilometers

Therefore, the boiling point of water is between 84°C and 96°C at elevations of between 4.6 kilometers and 1.1 kilometers.