in the past, the number of customers using a drive-through window at aardvark bank has averaged 20 per hour, with a standard deviation of 3 per hour. this year, another bank opened up nearby. aardvark's manager believes this will result in a decrease in the number of customers. he recorded the number of customers who arrived during 36 randomly selected hours and found that the average number of customers per hour in the sample was 19.39. what is the p-value associated with this result?