Answer:
13%
Step-by-step explanation:
You want the simple interest rate that results in interest of $31,200 on $80,000 in 3 years.
Interest
The simple interest formula is ...
I = Prt
where P is the principal invested, r is the annual rate, and t is the number of years.
Filling in the given values, we can solve for r:
31200 = 80000·r·3
r = 31200/240000 = 312/2400 = 0.13 = 13%
The interest rate on Nancy's account was 13%.
