The best way to find out how many people can be accommodated in 3 hours, is to convert this to minutes, and then divide by 25 (as this will show how many times it can be ridden in the three hour period). 3 hours is equal to 180 minutes. Therefore, 180/25 is equal to 7 (with a remainder of 5 minutes). As there can be 7 slots of 55 people, you have to multiply these together, and this gives you 385 people. You still have 5 minutes remaining, and the best way to do this is to find the highest common multiple of 55 and 25, which is 5, and divide both of these by 5. Meaning that in 5 minutes, there are 11 people. You then have to add this to 385, giving you 396.
In order to find the hourly rate, just multiply the 11 riders in 5 minutes by 12 (as there are 12 lots of 5 in 60), and this will give you 132 people.
396 people are able to ride the Ferris Wheel in three hours.
The rate of people per hour is 132.
Hope this helps :)