t = 5.3 years
(about 5 years 4 months)
Equation:
t = (1/r)(A/P - 1)
Calculation:
First, converting R percent to r a decimal
r = R/100 = 7.2%/100 = 0.072 per year,
then, solving our equation
t = (1/0.072)((4835.6/3500) - 1) = 5.3
t = 5.3 years
Given that the number is x,
10% increase will give us a new number of:
110/100*x
=1.1x
10% decrease will give us a new number of:
90/100*1.1x
=0.99x
This implies the new number is less than the original number
D has the commutative property because it just flip flopped the numbers.
