hey guys, i hav the answers to this question which ive written in red, but i need to know the working out....

Portable telephones are first sold in the country Cellmania in 1990. During 1990, the number of units sold is 160. in 1991, the number of units sold is 240 and in 1992 it is 360.

In 1993 it was noticed that the annual sales formed a geometric sequence with first term 160, the 2nd and 3rd terms being 240 and 360 respectively.

a) what is the common ratio of this sequence?

Assume that this sales trend continues.

b) how many units will be sold during 2002?

c) in what year does the number of units sold between 1990 and 2002?

During this period, the total population of Cellmania remains approximately 80,000

e) use this information to suggest a reason why the geometric growth in sales would not continue

a) 1.5

b) 20,759

c) 1999

d) 61,958