3. Suppose that at 19 years old you win $100,000 playing the lottery. If you would like to have $1,000,000 when you retire at age 67 , determine the average rate of return needed under continuous compounding.
Q. 3. Suppose that at 19 years old you win $100,000 playing the lottery. If you would like to have $1,000,000 when you retire at age 67 , determine the average rate of return needed under continuous compounding.
Continuous Compounding Formula: We use the formula for continuous compounding: A=Pert, where A is the amount of money accumulated after n years, including interest, P is the principal amount, r is the rate of interest per year, and t is the time in years.
Plug in Values: First, let's plug in the values we know. We want A to be $1,000,000, P is $100,000, and t is the number of years from 19 to 67, which is 67−19=48 years.
Isolate Variable: Now we have $1,000,000=$100,000×e48r. To solve for r, we need to isolate it on one side of the equation.
Take Natural Logarithm: Divide both sides by $100,000 to get 10=e48r.
Apply Logarithm Property: Take the natural logarithm (ln) of both sides to get ln(10)=ln(e48r).
Solve for r: Using the property of logarithms that ln(ex)=x, we have ln(10)=48r.
Calculate Final Value: Divide both sides by 48 to solve for r: r=48ln(10).
Calculate Final Value: Divide both sides by 48 to solve for r: r=48ln(10).Calculate r using a calculator: r=48ln(10)≈0.05776226505 or about 5.78%.
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