Answer:
In the figure attached, the graph of the function is shown.
1. f(9) ≈ 6 means that at t = 9 (year 1977 + 9 = 1986) the cost to produce 1 watt of solar energy was $6
2. f(4) ≈ 25, which means at year 1981 (=1977 + 4) the cost was $25 per watt
f(3.5) ≈ 28, which means at half of year 1980 (=1977 + 3.5) the cost was $28 per watt
3. When f(t) = 45, t is equal to 2, which means that the year wass 1979 (= 1977 + 2)
4. From the graph we can compute the following table:
x | y
0 | 80
1 | 60
The general exponential decay formula is:
f(x) = a*b^x
where <em>a</em> is the initial value and <em>b</em> si the decay factor. Replacing with data from the table:
f(0) = a*b^0
80 = a
f(1) = a*b^1
60/80 = b
0.75 = b
