Group Sales And Sets
1. **Problem 1: Calculate total sales revenues for Kamukamu and Tweziimbe groups**
1. Given:
- Milk price per litre = 700
- Maize price per kg = 1000
- Beans price per kg = 3500
- 1 bag maize or beans = 120 kg
2. Calculate total revenue for each group and sales period:
- Kamukamu sales 1: 2520 litres milk, 35 bags maize, 10 bags beans
- Milk revenue = $$2520 \times 700 = 1764000$$
- Maize revenue = $$35 \times 120 \times 1000 = 4200000$$
- Beans revenue = $$10 \times 120 \times 3500 = 4200000$$
- Total = $$1764000 + 4200000 + 4200000 = 10164000$$
- Tweziimbe sales 1: 2314 litres milk, 41 bags maize, 9 bags beans
- Milk revenue = $$2314 \times 700 = 1619800$$
- Maize revenue = $$41 \times 120 \times 1000 = 4920000$$
- Beans revenue = $$9 \times 120 \times 3500 = 3780000$$
- Total = $$1619800 + 4920000 + 3780000 = 10349800$$
- Kamukamu sales 2: 3254 litres milk, 42 bags maize, 8 bags beans
- Milk revenue = $$3254 \times 700 = 2277800$$
- Maize revenue = $$42 \times 120 \times 1000 = 5040000$$
- Beans revenue = $$8 \times 120 \times 3500 = 3360000$$
- Total = $$2277800 + 5040000 + 3360000 = 10697800$$
- Tweziimbe sales 2: 2719 litres milk, 32 bags maize, 11 bags beans
- Milk revenue = $$2719 \times 700 = 1903300$$
- Maize revenue = $$32 \times 120 \times 1000 = 3840000$$
- Beans revenue = $$11 \times 120 \times 3500 = 4620000$$
- Total = $$1903300 + 3840000 + 4620000 = 10363300$$
2. **Problem 2: Determine student counts fitting different sizes**
Given:
- Medium = Large = 100 students
- Small = 76
- Small & Large = 50
- Medium & Large = 70
- Small & Medium = 60
- None = 4
- Total students = 140
- Some fit in all three sizes (x)
Using inclusion-exclusion principle for three sets:
Total in at least one size = Total - None = $$140 - 4 = 136$$
Formula:
$$ ext{Small} + ext{Medium} + ext{Large} - (SM + SL + ML) + ext{All three} = ext{At least one}$$
Plug in values:
$$76 + 100 + 100 - (60 + 50 + 70) + x = 136$$
$$276 - 180 + x = 136$$
$$96 + x = 136$$
$$x = 40$$
So, 40 students fit in all three sizes.
3. **Problem 3: Determine the number of students liking foodstuffs**
Given:
- Prices: posho 20,000, rice 30,000, cassava 10,000 (not needed for set problem)
- Likes: Cassava (C) = 47, Posho (P) = 53, Rice (R) = 45
- Only posho = 23, only cassava = 10, only rice = 5
- All three = 15
Find students in combined groups:
Using inclusion-exclusion:
Calculate first the number who like at least one foodstuff:
$$|P \cup C \cup R| = |P| + |C| + |R| - |P \cap C| - |P \cap R| - |C \cap R| + |P \cap C \cap R|$$
We know:
- Only posho = 23 = $$|P| - |P \cap C| - |P \cap R| + |P \cap C \cap R|$$
- Only cassava = 10
- Only rice = 5
- All three = 15
Compute pairs intersections:
Let:
$$a = |P \cap C|, b = |P \cap R|, c = |C \cap R|$$
From only posho count:
$$23 = 53 - a - b + 15 \, \Rightarrow \, a + b = 53 - 23 + 15 = 45$$
From only cassava count:
$$10 = 47 - a - c + 15 \, \Rightarrow \, a + c = 47 - 10 + 15 = 52$$
From only rice count:
$$5 = 45 - b - c + 15 \, \Rightarrow \, b + c = 45 - 5 + 15 = 55$$
Summing:
$$(a + b) + (a + c) + (b + c) = 45 + 52 + 55 = 152$$
But this equals $$2(a + b + c)$$ so:
$$2(a + b + c) = 152 \Rightarrow a + b + c = 76$$
Using sums:
$$a + b = 45$$
$$a + c = 52$$
$$b + c = 55$$
Subtract pairs to find individuals:
Subtract first from second:
$$(a + c) - (a + b) = 52 - 45 \Rightarrow c - b = 7$$
Subtract first from third:
$$(b + c) - (a + b) = 55 - 45 \Rightarrow c - a = 10$$
From $$c - b = 7$$ and $$c - a = 10$$, rearranged:
$$c = b + 7$$
$$c = a + 10$$
Thus:
$$b + 7 = a + 10 \Rightarrow b = a + 3$$
Recall $$a + b = 45\Rightarrow a + (a + 3) = 45 \Rightarrow 2a = 42 \Rightarrow a = 21$$
Then:
$$b = 24$$
$$c = a + 10 = 31$$
Final counts:
- Posho & Cassava = 21
- Posho & Rice = 24
- Cassava & Rice = 31
This fully describes the set intersections.
**Final answers:**
- Problem 1 totals: Kamukamu1=10164000, Tweziimbe1=10349800, Kamukamu2=10697800, Tweziimbe2=10363300
- Problem 2 all three fit: 40
- Problem 3 intersections: P\&C=21, P\&R=24, C\&R=31