Answer:
Step-by-step explanation:
You could do this step by step.
The first year is left alone: 90,000 kt
The second year is 90000 * 0.96 That represents a 4% reduction
Second year = 86400
Third year = 86400 * .96 = 82944
Fourth year = 82944 * 0.96 = 79626.24 Here's where you run into your first dilemma. What do you do with that 0.24? The answer is, you round it here, but leave it in your calculator.
Fourth year = 79626
Fifth year = 79626.24 * 0.96
Fifth year = 76441
Sixth year = 79626.1904 * 0.96
Sixth year = 73383.542
Sixth year = 73384
Of course once you have gone through all that, you could do it this way
Sixth year = 90000 * 0.96^(n - 1) = 73383.54 = 73384
Same answer both ways.
I'm going to leave the addition to you.
Sum = a* (r^(n) - 1)/ (r - 1)
Sum = 90000 * (0.96^5 - 1) / (0.96 - 1 ) = 415411 rounded. I think that's right, but check it out.
