Answer:
To find the average rate of change of S(t) during the first year, we need to consider the change in the number of units sold over the first 12 months.
(a) To calculate the average rate of change, we need to find the difference in the number of units sold between the initial time (t=0 months) and the end of the first year (t=12 months).
So, let's evaluate S(t) at t=0 months and t=12 months:
S(0) = 20(5 - 6 + 0/9) = 20(5 - 6) = 20(-1) = -20
S(12) = 20(5 - 6 + 12/9) = 20(5 - 6 + 4/3) = 20(5 - 6 + 1.33) = 20 * 0.33 = 6.6
Now, we can calculate the average rate of change:
Average rate of change = (S(12) - S(0)) / (12 - 0)
= (6.6 - (-20)) / 12
= (6.6 + 20) / 12
= 26.6 / 12
= 2.2167 (rounded to 4 decimal places)
Therefore, the average rate of change of S(t) during the first year is approximately 2.2167.
(b) To determine the month during the first year when S(t) equals the average rate of change, we need to solve the equation S(t) = Average rate of change.
Let's set up the equation:
20(5 - 6 + t/9) = 2.2167
Simplifying the equation:
100 - 120 + t/9 = 2.2167
-20 + t/9 = 2.2167
t/9 = 2.2167 + 20
t/9 = 22.2167
t = 22.2167 * 9
t ≈ 199.95
Therefore, during which month of the first year does S(t) equal the average rate of change, approximately?
It seems there is an error in the equation or calculation as the value of t exceeds 12 months. Please double-check the equation or provide additional information for a more accurate analysis.