The wind-chill index (in degrees C) is modeled by the function W = 13.12 + 0.6215T − 11.37v0.16 + 0.3965Tv0.16 where T is the air-temperature (°C) and v is the wind speed (km/h). When T = −9°C and v = 46 km/h, at what rate is windchill changing as air-temperature increases? (Round your answers to two decimal places.) Incorrect: Your answer is incorrect. °C of windchill per °C of air-temperature When T = −9°C and v = 46 km/h, , at what rate is windchill changing as wind-speed increases?