From the information given, the deposit is 4000$, interest rate is 2.75% the final interest amounts to 220$ but the time it will take to earn this interest is unknown. We will assume the interest earned is per annum.
The formula we use is I = Prt
Let simple interest be I which is 220
Let principal sum be P which is 4000
Let interest rate be r which is 2.75 %
Let time be t
We need t, so we say t = I / Pr
t = 220 / 4000 * 2.75/100
t = 220 / 4000 * .0275
t = 220 / 110
t = 2
Therefore the time it will take to earn 220 $ interest is 2 years.
