Answer:
End of year 3: $677.85
Explanation:
If the interest rate is annual effective:
Year 0 (now): $100
In a year from now I will have:
End of Year 1: $100*1,075= 107.5
Then I put $200 more, i will have $307.5
Begging of year 2: $307.5
In two years from now I will have:
End of year 2: $307.5*1.075= $330.56
Then I put $300 more, i will have $660.56
Begging of year 3: $660.56
In three years from now i will have:
$660.56*1,075= $677.85
End of year 3: $677.85