In the summer, humidity interacts with the outdoor temperature, making a person feel hotter because of reduced heat loss from the skin caused by higher humidity. The temperature-humidity index, Th, is what the temperature would have to be with no humidity in order to give the same heat effect. One such index is given by the function below, where T is the air temperature, in degrees Fahrenheit, and H is the relative humidity, expressed as a decimal.

Th= 1.99T -1.08 (1-H)(T-56) -56.4

1. dth/dh=

2. (Multi Choice) A.The partial derivative shows that where T<56,Th will increase by a factor of 1.08

units. Where T56, Th will decrease by a factor of 1.08 units.

B.The partial derivative shows that where T<56, Th will increase by a factor of 1.08

units. Where T>56, Th will decrease by a factor of 1.08 units.

C.The partial derivative shows that where T56, Th will decrease by a factor of

1.08 units. Where T<56, Th will increase by a factor of 1.08 units.

D. The partial derivative shows that where T>56, Th will increase by a factor of 1.08

units. Where T<56, Th will decrease by a factor of 1.08 units.