HELP with UML

UML
1

i have a few questions that i need to answer on UML, and i am stuck on it is there anyone that can help me out with the questions.

thank you

Chipolata Buses of Marlin on Sea plan to invest in a new bus card system. In addition to a travel card (monthly, weekly, daily), there is a pre-pay card (pay-as-you-go), where customers can purchase credit in advance, and a concessions card, allowing free off peak travel for certain groups of people. Each bus is to be fitted with a card reader which will read the card, update the amount of credit (for pre-pay) or check it is valid (travel cards or concession cards). Different fares are charged for peak and off peak services. If the card is not valid for some reason (e.g. out of date, no credit or can’t be used at peak times) the reader should give an audible warning to prompt the driver to read the display and take appropriate action. The reader should also give a valid “beep” so that the driver and passenger know that the card has been read.
The pre-pay card needs to be debited each time it is used. However, there is a daily cap so that it never exceeds the amount that would be charged for a daily travel card. There is a flat fare for each journey, but peak journeys (before 9.30 am) cost more than off peak journeys. The amount charged is displayed.
Current costs:
Daily travel card £6
Weekly travel card£35
Monthly travel card£120
Single peak journey£2
Single off peak journey£1

  1. Given the following Use Case Diagram, supply an appropriate Use Case Description(s)

[img=http://img408.imageshack.us/img408/3064/untitledag5.th.jpg]

the diagram is provided above link

2

I assume that you asking how to describe a use case?

Check VP they have some templates that you can use.

The use case description mainly has (but not limited to)

Pre-condition
MSS

Alternative path
Exception path

Post-condition.

But I am not sure what you are asking. The use case diagram provided is a bit odd and I think it is missing some actors (eg where are we checking that the card credit etc sure there will be some sort of external system involved in that).

Anyway specify you questions and we might be able to help.

H