Final answer:
To determine the effective rate of interest in year 8, calculate the difference in the accumulation function between years 8 and 7, then divide it by the accumulation in year 7.
Step-by-step explanation:
To determine the effective rate of interest in year 8, we need to calculate the difference in the accumulation function between year 8 and year 7, and then divide it by the accumulation in year 7.
Using the given accumulation function a(t) = 2t²+3t+1, we can substitute t = 8 and t = 7 to find the accumulation in year 8 and year 7, respectively.
Then, we can plug these values into the formula for effective rate of interest: lₜ = [a(t) - a(t-1)] / a(t-1).
Calculating this expression will give us the effective rate of interest in year 8.