Answer:
C. An investment of $4,500 will double in 8 years at a compound interest rate of 9%.
Step-by-step explanation:
Since, according to rule of 72,
An investment is doubled in a fixed annual rate of interest when the product of time ( in years ) and annual rate ( in percentage ) is 72.
In option A :
Annual rate of interest = 5 % and time = 12 years,
But, 5 × 12 ≠ 72,
Thus, option A is incorrect.
In option B :
Annual rate of interest = 7 % and time = 10 years,
But, 7 × 10 ≠ 72,
Thus, option B is incorrect.
In option C :
Annual rate of interest = 8 % and time = 9 years,
But, 8 × 9 = 72,
Thus, option C is correct.
In option D :
Annual rate of interest = 12 % and time = 4 years,
But, 12 × 4 ≠ 72,
Thus, option D is incorrect.
