Worldwide, wind energy generating capacity, W, was 236,733 megawatts at the end of 2011 and 371,374 megawatts at the end of 2014. (Generating capacity is the maximum rate at which energy can be produced, measured in this problem in megawatts.)

(a) Use the values given to write W, in megawatts, as a linear function of t, the number of years since 2011. 

(b) Use the values given to write W as an exponential function of t. 

(c) Graph the functions found in parts (a) and (b) on the same axes. Label the given values.

(d) Use the functions found in parts (a) and (b) to predict the wind energy generating capacity in 2015. Generating capacity at the end of 2015 was 434,944 megawatts. Which estimate is closer to the real value?