Final answer:
To find the required gradient, calculate the present worth of income for each year and solve the equation to find g.
Step-by-step explanation:
To find the required gradient, we need to calculate the present worth of income for each year from 4 to 15, and then find the constant gradient that would result in a present worth of $13,500,000. The present worth of income for each year can be calculated using the formula for present worth:
P = A / (1 + r)^n
where P is the present worth, A is the future value (income in this case), r is the interest rate, and n is the number of years.
Substituting the values into the formula, we get:
P4 = $200,000 / (1 + 0.12)^4 = $122,386.28
P5 = P4 * (1 + g) = $122,386.28 * (1 + g)
P15 = P4 * (1 + g)^11 = $122,386.28 * (1 + g)^11
Setting the sum of the present worths equal to $13,500,000:
P4 + P5 + ... + P15 = $13,500,000
$122,386.28 + ($122,386.28 * (1 + g)) + ... + ($122,386.28 * (1 + g)^11) = $13,500,000
This equation can be solved for the required gradient, g, using algebraic techniques such as factoring or substitution.