David invested $220 in a savings account that offers a 3% return on the investment. The value of David's investment will be at least $400 after a period of years.
Hi there The formula is A=p (1+r)^t A future value 400 P present value 220 R interest rate 0.03 T time? We need to solve for t A=p (1+r)^t divide both sides by p to get A/p=(1+r)^t take the log Log (A/p)=t×log (1+r) divide each side by log (1+r) to get T=log (A/p)÷log (1+r) Now plug the numbers above T=log(400÷220)÷log(1+0.03) T=20.2 years round your answer to get T=20 years
