In 1911, the first year of the Indianapolis 500 auto race, the winning car had an average speed of 109.416 feet per second. What is that speed in miles per hour?

74.6018 Miles per hour

Step-by-step explanation:

Step 1: How many seconds are in an hour? There are 60 seconds in a minute and 60 minutes in an hour, so there are 60*60 = 3600 seconds in an hour.

Step 2: How many feet are in a mile? There are 5280 feet in a mile.

Step 3: To convert feet per second to miles per hour, first multiply by 3600, then divide by 5280. The fraction 3600/5280 reduces to 15/22.

To convert feet per second to miles per hour, multiply by 15/22.

So: 109.416 feet/second * (15/22) = 74.6018 miles/hour