One of your neighbours has fallen down on his luck and would like to sell a camper van to raise some money. He sets the purchase price at $20,000. You would like to buy the van but don't have the money right now. Your neighbour offers to let you buy the van if you pay "only" $630.00 per month for 3 years. (a) What monthly interest rate (per month compounded monthly) is the neighbour charging you? (Note this is an iterative calculation - one significant figure is fine - interest rate is less than 1% pmcm)