Answer:
Let r be the monthly interest rate: r = .08/12, and a = 1+r
Balance after 3 years
= 1000a^36 + 25a^35 + 25a^34 + ... + 25a, assuming the last deposit earn one month interest.
= 1000a^36 + 25a(1-a^35)/(1-a)
= $2258.63 <==Answer
Attn: If the last contribution doesn't earn any interest, then the final balance should be 2258.63 + 25 = $2283.63.
Explanation: