Question

You deposit $800 in an account that earns simple interest at an annual rate of 5%.
How long must you leave the money in the account to earn $100 in interest?

Answer 1

Step-by-step explanation:

$800 × 5% = $40

for 1 year, I earn $40

100 ÷ 40 = 2 remainder 2

Therefore I would have to leave the money in for at least 3 years to earn $100

Answer 2

Answer: 2.5 years

Step-by-step explanation:

The formula to calculate the simple interest is given by :-

$I=Prt$, where P is the principal amount , r is the rate of interest ( in decimal) and t is time ( in years).                                              

Given : P= $800   ; r= 5% =0.05   and  I=$100

Then , we have

$100=800\times0.05t\\\\\Rightarrow\ t=\dfrac{100}{800\times0.05}=2.5$

Hence, you must leave the money in the account for 2.5 years to earn $100 in interest.