Since Kristine has been a long-time loyal customer, Kristine is able to place a rush order at $30 ($15 premium in addition to the regular price of $15) per pound in late morning and have it delivered by the local market provider within an hour from the order time. Kristine is considering this option, because, by late morning, she knows for sure what the demand will be for the day. What is the probability that the size of the rush order is at least 20 pounds?