00:01
Okay, this question asks us about a situation where we have four cereals and four add -ins, and it asks us different questions about the number of breakfasts people can make.
00:11
So part a says we have to include at least one cereal or add -in.
00:16
So the number of subsets possible with this is equal to, as we said, 2 to the n, or 2 to the 8th in this case, which is 256.
00:31
But not all of those subsets are valid breakfasts because we need at least one cereal or add -in.
00:40
So we need to subtract away the one subset where there's nothing.
00:46
So we get 255 for the number of breakfasts.
00:52
Then for b, it says one cereal and one add -in.
00:58
So we have a cereal choice where we have four options, and then we have an add -in choice where we have four options.
01:07
So it's just 4 times 4, which is 16.
01:12
Then for part c, we have two serials and three add -ins.
01:21
So we have four cereals, and we're picking two of them, times we have four add -ins, and we're picking three of those.
01:30
So it's just four choose two times four choose three, which gives us 24 different options for this one.
01:44
Then for part d, it says we need at least one cereal and at least one add in.
01:53
So i'd start by having the 256 total potential breakfasts minus the ones we don't need...