1. For a patented product, after advertising on TV stations in January 2007, the sales volume of the product in March quadrupled compared to the first month. The average monthly sales growth rate is .
2. A rectangular landscape painting with a length of 80 cm and a width of 50 cm is surrounded by a golden paper edge of the same width to make a rectangular wall chart. If the area of ??the entire wall chart is to be 5400㎝2, assuming that the width of the golden paper edge is x㎝, then the equation that x satisfies is Calculation of interest), the sum of principal and interest is 302.16 yuan, then the monthly interest rate of current savings is