4. a bike rental company rented out 8 bikes in its first month. the company increased the number of bikes it rented each month by 2%. what was the approximate total number of bikes the company will rent out for the first 9 months?

50

59

68

78

This is a geometric sequence:

First month: 8
Second month: 8 * 1.02
Third month: 8*1.02^2
Fourth month 8* 1.02^3
...
nth month: 8 * 1.02 ^(n-1)

Sum of the first 9 terms (months) = a[1 -r^n] / (1 - r) = 8* [1 - 1.02^9] / (1 - 1.02) = 78.04

approximately 78 bikes.