Question

On your birthday you received $100 which you invested at 6.5% interest, compounded annually. That investment is now worth $3,500. How many years have past?

Answer 1

Future value	FV=	PV × (1+r)^N
Payments to achieve future value	N=	Log(FV/PV)/ Log(1+r)
Future value	FV=	3,500
Present value	PV=	100
Interest rate:
Stated rate		6.5%
/ number of compounding periods per year		1
Interest rate per period	r=	6.5%
Periods to achieve future value	N=	Log( 3500/100 )/ Log( 1+ 0.065 )
	N=	56.46
Years to achieve future value	=	56.46

Numer of years past is 56.46