Answer:
The doubling time of this investment would be 9.9 years.
Step-by-step explanation:
The appropriate equation for this compound interest is
A = Pe^(rt), where P is the principal, r is the interest rate as a decimal fraction, and t is the elapsed time in years.
If P doubles, then A = 2P
Thus, 2P = Pe^(0.07t)
Dividing both sides by P results in 2 = e^(0.07t)
Take the natural log of both sides: ln 2 = 0.07t.
Then t = elapsed time = ln 2
--------- = 0.69315/0.07 = 9.9
0.07
The doubling time of this investment would be 9.9 years.
10% off
= $4.80
30% off
= $4.80 x 3
= $14.40
$48 + $14.40
= $62.40
The original price was $62.40
