To boost holiday sales, a jewlery store in Bismark, North Dakota is advertizing the following promotion: "if more than 7 inches of cumulative snow fall on December 14, 25, 26, 27, 28you get your money back on all purchases made on December 17." To analyze this promotion the store manager has collected data and determined that snow fall over this 5 day period in December is normally distributed with an average of 6 inches and a standard deviation of 0.559 inches. What is the probability that the store will have to refund the money to it's December 17 customers?