Martin deposits $200 in a savings account that earns 5% annual interest. four years later, cary deposits $200 in an account earning the same interest. let m represent the balance in martin’s account and let c represent the amount of money in cary’s account. choose the pair of expressions that describe the accounts y years after martin opened his account. martin: 200(1.05)y cary: 200(1.05)y+4 martin: 200(1.05)y+4 cary: 200(1.05)y–4 martin: 200(0.05)y cary: 200(0.05)y–4 martin: 200(1.05)y cary: 200(1.05)y–4

Martin deposits $200 in a savings account that earns 5% annual interest.

year         interest                       balance

1              200 * 5%                    200(1.05)

2              200(1.05) * 5%          200(1.05)^2

3              200(1.05)^2*5%        200(1.05)^3

y                                                200(1.05)^y

=> m = 200 (1.05)^y

four years later, cary deposits $200 in an account earning the same interest.


year         interest                       balance

5              200 * 5%                    200(1.05)

6              200(1.05) * 5%          200(1.05)^2

7             200(1.05)^2*5%        200(1.05)^3

y                                                200(1.05)^(y-4)

=> c = 200(1.05)^ (y-4)


Martin: 200(1.05)^y
Cary: 200(1.05)^(y–4)