The simple interest formula is the following: A=P(1+rt) A=amount accumulated (or how much there will be in the account at the end of 21 years) P=Principal (how much money we start with. In this case is $300) r=interest rate in decimals (0.055 in this case. We got this number by converting 5.5% into decimals. You do this by dividing 5.5 by 100) t=time. 21 years in this case Let's now go ahead and solve for A: A=300(1+0.055*21) 0.055*21=1.155 A=300(1+1.155) A=300(2.155) A=646.50 At the end of 21 years you will have $646.50 in your bank account.
