00:01
In question a, we want to find the number of different ways four letters can be taken from the word liberty and be arranged without repetition.
00:11
Now, the word liberty, all the letters are unique.
00:15
There are no repeats and in total there are seven letters.
00:19
So the four letters can be chosen from the seven letters will be seven choose four.
00:29
But take note that the four letters can be arranged among itself or permutated among itself.
00:35
So that will be times four factorial way of permutating among themselves.
00:42
Now, all this is equivalent to 7p4.
00:47
Seven letters you permutate 4.
00:50
And that will be 840 ways.
00:55
Now, in b, we want to find number of ways you can select a committee of five students.
00:59
Out of 12 students.
01:04
Here, there is no order after you select the 5 students.
01:08
They are not arranged in any particular order...