How to calculate percentages with an if in access.

[leates]

Hello,

I am looking to have a textbox in a form in access, displaying the exam first time pass rate for the people in the database.



The table is called Pupils, and has an ID, which is the Primary Key, it also has a field called "Passed", and one called "First time", both being boolean tick boxes.

I need the text box in the form to work out the percentage of people who have passed, and did it first time.

If you need any more information, please don't hesitate to ask!

Thanks!

[leates]

Also, it only needs to consider the people that have passed!