automatically choose from dropdown menu by referencing cell values

Greetings!

Working at a university, I need to enter grades of my students in the school provided the excel sheet. There is process which I am sure can be performed automatically but none of my colleagues knew of it. I googled for a couple of days during my free time but was not very helpful given my shallow knowledge about excel.

What I need to do is the following:
(See the attached "sample.xls")
If the value of the column E (grade input) is above some threshold (say 40) then, the column F (exam board note, drop-down menu) becomes automatically P [Pass], otherwise it is left unchanged.

(Think that there are 200 students! And P [Pass] is located down below so I need to scroll down to be able to click it. This is really annoying and unproductive task!)

There are constraints: From the original excel file, (1) columns H and I (yellow coloured) are invisible. It was visible only when I pasted it into another excel sheet. Obviously they constructed the dropdown menus -column F and G from these columns and hid them by some tricks , and (2) the original file is password protected. (3) I want to maintain this stupid dropdown menu so that I don't get annoyed (and annoying) email from admin staffs that he/she cannot upload it to the system because of the reason they don't know. Absent these constraint, I could achieve my objective my using a function like " IF(cell>40, reference to the cell whose value is P [Pass]. ".

Any feedback/thoughts would be greatly appreciated.

Thanks in advance!