Question

question 4
beckys brothers investment earns 13% annually. about how long will it take for his money to double?
answer

question 5
beckys brothers investment has a 13% return but loses 2% annually in fees. how much longer will it take to double his money after fees?
answer

Explanation:

Step1: Apply Rule of 72 (Q4)

$\text{Time to double} = \frac{72}{\text{Annual interest rate}}$
$\text{Time} = \frac{72}{13} \approx 5.54$ years

Step2: Calculate net rate (Q5)

$\text{Net rate} = 13\% - 2\% = 11\%$

Step3: Apply Rule of 72 (Q5)

$\text{Time to double} = \frac{72}{11} \approx 6.55$ years

Step4: Find time difference (Q5)

$\text{Extra time} = 6.55 - 5.54 = 1.01$ years

Answer:

Question 4: About 5.5 years
Question 5: About 1 more year (total ~6.6 years)