Question

suppose we want to choose 2 letters without replacement from four letters ABCD. (A)how many ways can the speed on if the order of choices is taken into consideration?(B) how many ways can this be done if the order of choices is not taken into consideration ?

Answer 1

A)

If the order of choice is taken into consideration, we consider four possibilities for the first choice and three for the second. Then the total number of ways is given by:

`4\cdot3=12`

B)

If the order of choices is not taken into consideration, we must divide the the previous result by 2, which is the total number of ways by which we can organize two letters (ex: AB and BA):

`(12)/(2)=6`