Melody

This has been asked and answered many times before.

there are 21 possible chords and you want 4 of them so that is   21C4 = 4985 possible combinations.

To make a bow tie you need just 4 points out of 7   which is  7C4 = 35 combinations

But how many possible bow ties can you get out of a specific 4 points?  You work it out.

And then you finish it.

I think it is a stupid question too.

I will assume that all the socks of each colour are identical.

At a minimum 2.  she might get lucky

At a maximum 6.  She might pull out one of each colour before finally pulling out a second of any.

Ok, sorry that explains it.

You can always send a private message to  a moderator asking them to unlock a question.

Also you can still put a link to the original and explain that it is, and, may continue to be locked.

You could also comment on my new answer on the old thread, as that thread is no longer locked.

A note for next time:

If you know the answer is wrong you should say so on the original. (with your reason given)

And if you knew that the original quation was there, this one should have been done as a repost.

(With the address of the original)

I have answered on the original thread.

a and b have 7 prime factors in common.

a*b has 28 prime factors

so the number of prime factors of a or b that are not common to both is 21

a has less prime factors than b so at most 10 of these 21 extra prime factors belong to a

So the most prime factors that  a  can have is  7+10 =17

Yes, I think it is.

You can just use any right-angled triangle (and ignore the minus signs)

But you have to think about the minus afterwards to get the right quadrants.

This is not all that hard.

Let x be  the number of students in the class

so  x/2  are less than 12

x/6 are  are older than 13

So what fraction are between 12 and 13?

Can you take it from there?  Show us what you can do?