invested 2000

Question

gains 0.2 every odd numbered month
final value after first month?

i've tried solving this with a formula, but every formula i come up with is wrong.

Could someone tell me how to solve this and plug in the right numbers into a formula?

Answer 1

Are we to assume that there is a 20% gain for every odd-numbered month and for the even-numbered months the investment stays constant?

Since the "first" month would be odd-numbered, the amount after the first month would simply be
2000(1.2) = 2400

the "formula" would simply be
amount = 2000(1 + .2)^1

Answer 2

for every even-numbered number month there is a 15% gain.