Nested if function help immediately please

Hi
Im having my IGCSE ICT MOCKS tommorow and my teacher has posted a self made excel paper for us to do.
I have been stuck on the nested IF Function for hours now.
I would really appreciate if someone could show me the formula and tell me a little bit on how to do it as well.

Heres the question:
15) In cell A3, enter a function that works out the reward points using the average. The following criterion is used to work out the points.
a. If the student average is less than or equal to 4 then average multiplied by 2
b. If the student average is between 4 and 7 (inclusive) then average multiplied by 5
c. If the student average is above 7 then average multiplied by 10

Thank You

Im sorry but you seem to have misunderstoond,
This isnt homework - its just a task which we have been set because our mocks are tommorow.
I know homeowork is meant to be done by the student - but please understand this is not homework and merely a practice task which is not meant to be handed in.
And i have tried that method - i tried combining but then i get stuck.

Thanks

Here's basic syntax for nesting IFs

you have 3 conditions and resulting values
Condition 1) Average<4 : Value1) Average*2
Condition 2) Average<=7 : Value2) Average*5
Condition 3) Average >7 : Value3) Average*10

Test them one at a time.
=IF(Condition1,Value1,ValueIfFalse)

To nest the 2nd condition, put a new if in place of the ValueIfFalse
=IF(Condition1,Value1,IF(Condition2,Value2,ValueIfFalse))

Now since your conditions are mutually exclusive, we don't need a 3rd IF.
Because if the first 2 IF's are both false, we therefore know that the 3rd MUST be true
So you can just put Value3 in place of ValueIfFalse
=IF(Condition1,Value1,IF(Condition2,Value2,Value3))

Hope that helps.

Okay sorry i was being quite rude because i was in a hurry.
Sir Richard,
This is what I tried , but it didnt work , can you tell me whats wrong please ?

=IF(F3<=4,F3*2,IF(AND(F3>4,F3<=7,F3*5))

You're missing the closing ) for the AND function.
It should go right after the 2nd condition of the AND