12. An airplane travels due north at an airspeed of 800 km/h. It encounters a wind blowing at 70 km/h 650 east of north. What is the resultant velocity of the airplane? [5] 15. The population, P, of a bacteria colony at t hours can be modelled by: P(t) = 100 + 120t + 10t2 + 2+3 a. What is the initial population of the bacteria colony? [2] b. What is the population of the colony at 5 h? [2] c. What is the growth rate of the colony at 5 h? [3]