Question

How many ways can 6 books be chosen at random from a shelf with 12 books on it if the order is unimportant?

Answer 1

Use the formula for combinations since the order is unimportant. Do you know the formula?

Answer 2

Choosing b items from a items (a>b)
\[\text{No. of ways}= ^aC_b=\frac{a!}{(a-b)!\times b!}\]
I think you can do it now, can't you?

Answer 3

Is it something like
n!/((r!(n-r)!

Answer 4

Thanks