A systems analyst is designing a booking and tracking application for a boutique kayak rental business on a lake. The client provided the following description of their requirements:

"I run a kayak rental service on Lake Windermere. I want to automate my booking system. The base fee is £15 per hour. If a group rents 5 or more kayaks at the same time, they get a 'group rate' which is a 15% discount on the total bill. I prefer customers to pay using contactless cards, but cash is fine. I need to keep track of each customer's active security deposit—customers are uniquely identified by their email address. Some customers like to rent a wetsuit too, but we don't charge for that, we just need to log if they have one so we get it back. I always close the shop if it's raining heavily because I dislike getting wet. Also, any rental that goes even 1 minute over the hour is charged for another full hour (so a rental of 2 hours and 5 minutes is billed as 3 hours, which is £45)."

The developer has decided that the following two points are the only important details from the client’s request:

• The base rate is £15 per hour.
• Customers can rent wetsuits for free but their rental must be logged.