Permutation and Combination

[kontol]

So im having a bit of trouble understanding permutation and combination. I watched some videos on youtube and still confused. For the first question I think its combination but i have no idea how to do it. Second question I did the (a) part by doing 13!/2!*2!*2! which I believe is correct and the rest I'm not sure how to do.
Would really appreciate it if someone could help me.

 

[blamocur]

It seems to me you are right so far. for 2.b: If 'I' is fixed in the first position there still no restrictions on the remaining letters, i.e., it gets reduced to 2.a.

 

[Dr.Peterson]

For the first question I think its combination but i have no idea how to do it.

Please at least try (i). How many ways are there to choose 4 women out of 6?

For (ii), you'll be choosing men and women separately, and combining the results.

For (iii), three slots are already filled, so you just need to choose the fourth.

This is the basic idea behind solving these: imagine how you might make the choices, step by step.

 

[Steven G]

Suppose you pick x men from the 4 and y women from the 6.
This can be done in (₄C_X)(₆C_Y) ways