It is well known in Information Economics that an inferior

product with a large advertising budget sells very well when it is

introduced but sale decline as people discontinue the use of the

product due to its inferiority. Assume that the rate of change of

weekly sales is given by:

Where S is sales in cedis and t is time in weeks

a. Find a general function S(t) that describes the weekly sales

b. If in the first week, the sales was 100 cedis, find the specific

equation describing the weekly sales

c. Find the reduction in sales between the 4th and the 9th week.