00:01
So we've been given some information on various berries at a birthday party.
00:04
We want to know how many children ate raspberries and strawberries.
00:08
So i'm going to draw a venn diagram to display the information we've been given.
00:13
So we have a circle for raspberries, a circle for blackberries, and a circle for strawberries.
00:20
Now we need to fill this in.
00:22
When you're filling in a venn diagram, it's easiest to start right in the middle.
00:25
How many people meet all criteria? just alex.
00:28
So one person.
00:30
Out of the 30 ate all of them.
00:33
Okay, now we go out from the center and we see what we can do.
00:38
So we're told seven children ate blackberries and at least one other type of berry.
00:44
So this bit here adds up to seven.
00:49
Okay, and it looks like they're not going to tell us anything more.
00:53
Okay, let's fill in some information.
00:56
Just going to give all of these some values and see what we know.
01:01
We're going to have some simultaneous equations.
01:04
Raspberries is 14, so this group here adds up to 14.
01:07
A plus d plus e plus 1 is 14, so these three add up to 13.
01:13
12, 8 blackberries.
01:15
Oops, i forgot to put something here.
01:18
So b plus d plus f plus 1 is 12, so just those add up to 11.
01:25
16, 8 strawberries, strawberries.
01:26
So c plus e plus f plus 1 is 16.
01:30
So these add up to 15.
01:32
D plus f is 7.
01:38
And i know that if i were to add up all of these values plus the people who ate nothing, i would get 30 people.
01:46
Okay.
01:47
And my goal is to find the people who ate raspberries and strawberries.
01:51
I want e.
01:53
And i get that from my equation set.
01:55
I will bring out the big equation where they all add up to 30 if i have to...