According to Hooke’s Law, a linear relationship exists between the distance that a spring stretches and the force stretching it. Suppose a weight of 0.5 kilograms causes a spring to stretch 2.75 centimeters and a weight of 1.2 kilograms causes the same spring to stretch 6.6 centimeters.

(a) Find a linear model that relates the distance d of the stretch and the weight w. 

(b) What stretch is caused by a weight of 2.4 kilograms? 

(c) What weight causes a stretch of 19.8 centimeters?