Final answer:
To find the amount of rain that fell per hour, divide the total rainfall (2 1/4 inches) by the number of hours (18). Convert the mixed number to an improper fraction (9/4) and divide it by 18 to get 81/16 inches per hour.
Step-by-step explanation:
To find the amount of rain that fell per hour, we need to divide the total rainfall by the number of hours. In this case, the total rainfall is 2 1/4 inches and the number of hours is 18.
To divide a mixed number by a whole number, we first convert the mixed number to an improper fraction. 2 1/4 = 9/4. Then, we divide the numerator (9) by the denominator (4) to get the amount of rain that fell per hour: 9/4 / 18 = 9/4 * 1/18 = (9/4) / (4/18) = 9/4 * 18/4 = 81/16.
Therefore, the answer is 81/16 inches of rain fell per hour.