Chapter 6.2, Problem 46E

Temperature–humidity Heat Index.

In summer, higher humidity interacts with the outdoor temperature, making a person feel hotter because of reduced heat loss from the skin. The temperature-humidity index, $T_{\text{h}}$, is what the temperature would have to be with no humidity in order to give the same heat effect. One index often used is given by

$T_{\text{h}}=1.98T-1.09\left(1-H\right)\left(T-58\right)-56.9$,

where T is the air temperature, in degrees Fahrenheit, and H is the relative humidity, expressed as a decimal. Find the temperature-humidity index in each case. Round to the nearest tenth of a degree.

$\text{T=90}°f\text{ and }H=90\%$