Venn Diagram
1. **State the problem:**
We have 50 children choosing from beans, plantain, and rice.
Given:
- Total children = 50
- Beans = 21
- Plantain = 24
- Rice = 18
- Beans only = 3
- Plantain only = 9
- Rice only = 2
- All three items = 5
We want to find:
(a) Venn diagram illustration (described verbally here).
(b) Number of children who took:
(i) only plantain and beans
(ii) none of the three items
(iii) only rice and beans
2. **Define variables for pairwise intersections only** (excluding the all three):
Let:
- $x$ = number of children taking only beans and plantain
- $y$ = number of children taking only plantain and rice
- $z$ = number of children taking only rice and beans
3. **Write equations for each set total:**
For beans:
$$ 3 + x + z + 5 = 21 $$
$$ x + z = 21 - 3 - 5 = 13 $$
For plantain:
$$ 9 + x + y + 5 = 24 $$
$$ x + y = 24 - 9 - 5 = 10 $$
For rice:
$$ 2 + y + z + 5 = 18 $$
$$ y + z = 18 - 2 - 5 = 11 $$
4. **Solve the system:**
We have:
$$ x + z = 13 $$
$$ x + y = 10 $$
$$ y + z = 11 $$
Add first two equations:
$$ (x + z) + (x + y) = 13 + 10 $$
$$ 2x + y + z = 23 $$
But from third equation, $y + z = 11$, so:
$$ 2x + 11 = 23 $$
$$ 2x = 12 $$
$$ x = 6 $$
Then from $x + y = 10$:
$$ 6 + y = 10 $$
$$ y = 4 $$
From $x + z = 13$:
$$ 6 + z = 13 $$
$$ z = 7 $$
5. **Answer the questions:**
(i) Plantain and beans only = $x = 6$
(ii) Number who took none of the three items:
Total taking at least one = sum of all exclusive and overlapping groups:
$$ 3 + 9 + 2 + 6 + 4 + 7 + 5 = 36 $$
None took = $50 - 36 = 14$
(iii) Rice and beans only = $z = 7$
**Final answers:**
(i) 6
(ii) 14
(iii) 7
A Venn diagram would have the circles labeled Beans, Plantain, Rice with the regions:
- Beans only: 3
- Plantain only: 9
- Rice only: 2
- Beans and Plantain only: 6
- Plantain and Rice only: 4
- Rice and Beans only: 7
- All three: 5
- Outside all: 14