Is the sentence true or false?

Combination of two things from three given things a, b, c is ab, bc, ca.

Is the sentence true or false?

Permutation of two things from three given things a, b, c is ab, ba, bc, cb, ac, ca.

A flag has to be made by stitching three ribbons of different colors. There are a total of 5 ribbons of different colors. Find the number ways in which a flag can be made using these ribbons.

 John wants to invite about 5 guests from among his friends, for a party at his home. Which of the following would help to find different set of friends, whom John can invite for the party at his home

Complete:

To find the number of possible arrangements of dissimilar things, we use ________.

Complete:

When the order does matter, it is a ________.

Is the sentence true or false?

$\frac{P(n,r)}{C(n,r)}=r!$

Is the sentence true or false?

$P(n,r)=r!C(n,r)$

Is the sentence true or false?

A Permutation is an ordered Combination.

  Complete:

For grouping of things, or to get a count of the number of subgroups that can be obtained from the given set of things we use_____________.