The wind-chill index W is the perceived temperature when the actual temperature is T and the wind speed is v, so we can write W = f(T, v). The following table of values was compiled by the NOAA Weather Service of the United States and the Meteorological Service of Canada. Wind speed (km/h) Actual temperature (C) V T - 10 -15 - 20 -25 20 - 18 -24 -30 -37 30 - 20 - 26 -33 - 39 40 - 21 -27 -34 - 41 50 -22 - 29 -35 - 42 60 - 23 -30 -36 - 43 70 -23 - 30 -37 - 44 (a) Estimate the value of f(-20, 40). (Use f(-25, 40) and f(-15, 40).) What is the practical interpretation of this value? When the actual temperature is -20 C and the wind speed is 40 km/h, the apparent temperature increases by about for every degree that the actual temperature rises. Estimate the value of f(-20, 40). (Use f(-20, 30) and f(-20, 50). ) C

The wind chilt index W is the percelved temperative when the actual temperature is T and the wind speed is V, so we car wite W=rT,V). The foliowing table of values was compiled by the NOAA Weather Service of the United States and the Meteorological Service af Canada. Wind aneat kim/h Ial Eatimate the value of r(20,40) (Une N(25,40) and f(15,40),1) What is the practical inserpretation of this value? When the actual temperature is 20C and the wind speed is 40km/m, the apparent tempecature increases by about for every degree that the actual temperature rises. Estimate the value of f(20,40) (Use f(20,30) and f20,50).) What is the practical interpretation of this value? When the actual temperature is -20 * C and the wind speed is 40km/h, the apparent temperature decreases by about for every km/h that wind speed increases. (b) In general, what can you say about the signs of dw/ar and dW/dv? (Select all that apply.) For a fixed wind speed v, the values of the wind-chill index. W increase as temperature T increases, 50 aW/at is positive For a fixed temperature T, the values of W increase as v increases, so dW/JV is negative: For a fixed temperature T, the values of W increase as v increases, so dW/v is positive: For a fuxed temperature T, the values of W decrease as v increases, so aW/av is negative For a fixed wind speed v, the values of the wind-chill index W decrease as temperature T increases, so dW/at is negative (c) What appears to be the value of the following limit? limvvW