Cie as level paper 6

the permutations question was easy!

i got one little query though-what was your answer to no.2 where they ask for the probability for time taken between 5-10 minutes? it was of only one mark.

We just had to subtract the 2 probabilities. So the ans was 0.72 . What was your ans to the question of "exactly 6 letters between 2 W" mine was 20160 :/

I got 3720 but I am not really sure about it since I considered them asking us an 8 letter alphabet. But my friend said it should be a 10 letter one and if that is the case, it would become different.

We just had to subtract the 2 probabilities. So the ans was 0.72 . What was your ans to the question of "exactly 6 letters between 2 W" mine was 20160 :/

Yea we had to consider a 10 letter alphabet not 8 .

Then 22320

Nah I don't think so.
We had to first consider 3Ls between 2W then 2L between 2W then 1L then add them up.

This is exactly what I did.

With three Ls, you need to add a combination of 3 alphabets so 5C3
Multiply it by 6P6 because 6 numbers and divide by 3!
Repeat wit 2 L: 5C4*6P6/2!
With 1L: 5C5*6P6
We can consider W to W as a whole and 2 letters are left out so multiply the sum of previous example with 3! (This, I missed)

This is how I did it:
So first 3Ls between the the 2 W so we need three more letters from 5 more so 5C3, then arranging so
5C3*(6!/3!)*3! = 7200
Then 2Ls : 5C4*(6!/2!)*3! = 10800
Then 1L : 5C5*6!*(3!/2!) = 2160
Total arrangements = 7200+10800+2160=20160.

I bet you will score 2/4 marks for method (which isn't too bad)