Final answer:
The elephant's running speed of 1/4 mile in 36 seconds is equivalent to 25 miles per hour, after converting 36 seconds to hours and dividing the distance by the converted time.
Step-by-step explanation:
To calculate the rate at which the elephant runs in miles per hour, we first convert 36 seconds into hours. We know that there are 3600 seconds in one hour. So, the time it takes for the elephant to run 1/4 mile is 36 seconds / 3600 seconds/hour = 0.01 hours. Next, we find the speed in miles per hour by dividing the distance by time. The elephant runs 1/4 mile in 0.01 hours, giving us a speed of 1/4 miles / 0.01 hours = 25 miles per hour. Therefore, the correct option that shows the elephant's rate as miles per hour is '36 seconds = 25 miles per hour'.