AB2. (a) Since April 1 is 3 months from January 1 and June 30 is 3 months later, we form the sum
for the interval [3,6]:
We estimate the company sold 1051 software units during the second quarter.
(b) S(t) = 1.2(2)t/3
(c) The model’s estimate of 1039 sales is slightly lower, but the two are in
close agreement.
(d) the model predicts an average sales rate of 649.2 units per month from
January 1, 2012, through December 31, 2012.