Final answer:
To find the average speed of the dolphin, divide the total distance traveled by the total time taken. In this case, the dolphin swam 7 1/2 miles in 3/8 hour. Therefore, the average speed of the dolphin is 20 miles per hour.
Step-by-step explanation:
To find the average speed of the dolphin, we need to divide the total distance traveled by the total time taken. In this case, the dolphin swam 7 1/2 miles in 3/8 hour. To divide fractions, we multiply the first fraction by the reciprocal of the second fraction. So, 7 1/2 ÷ 3/8 = 15/2 ÷ 3/8. To divide fractions, we multiply the first fraction by the reciprocal of the second fraction. So, 15/2 ÷ 3/8 = 15/2 × 8/3 = 120/6 = 20. Therefore, the average speed of the dolphin is 20 miles per hour.