00:01
You have two nickels, one dime, and one half dollar.
00:06
In how many ways can we select one or more coins? let's look at some characteristics of this problem.
00:16
One characteristic is that as we select the coins, order is not important.
00:27
Another characteristic is that two of the coins are identical.
00:40
Let's look at some formulas that we can.
00:43
Can potentially use.
00:46
So let's look at this formula combination and taken r.
00:55
The assumption here is that we have n different objects to choose from.
01:13
And order is not important.
01:15
But in our problem, two of the objects, two of the coins, are identical.
01:24
So we don't have four different objects.
01:26
So we cannot use this formula.
01:31
How about permutation rule number two? this formula here where you have n objects where r1 are identical r2 are identical and so on.
01:49
Now it's a permutation formula which means order is important so we cannot use that either.
02:02
In fact the best way to solve this problem is it's just by listing all the different ways and then just counting the number of ways...