Businesses that offer repayment plans for purchases are required by law to disclose the interest rate. But that doesn't mean they go out of their way to let you know what it is. You have to read all the paperwork. Find the interest rate for the following purchase. To finance a new laptop, Emilie is offered a 4 year payment plan with low monthly payments of $34.10. The cost of the laptop was $884.02 including tax. Round to one decimal place, if necessary. The interest rate is %.