The temperature of the water in a hot water tank is recorded at 15 minute intervals after the heater is switched on. \begin{matrix} \text{Time (x minutes)} & \text{15} & \text{30} & \text{45} & \text{60} & \text{75} & \text{90}\\ \text{Temperature} (y ^\circ C) & \text{20} & \text{30} & \text{40} & \text{50} & \text{60} & \text{70}\\ \end{matrix} Time (x minutes) Temperature(y ∘ C) ​ 15 20 ​ 30 30 ​ 45 40 ​ 60 50 ​ 75 60 ​ 90 70 ​ a. Plot a graph of these data on your GDC. b. Find the linear model, T(x), for the temperature of the liquid with respect to time. c. Find the temperature of the water after 85 minutes.