Tortilla Arrangements Fa423A
1. **Problem statement:** We have 2 different meat tortillas and 4 different vegetable tortillas to arrange on a plate. We want to find the number of ways to arrange them under different conditions.
2. **General formula for permutations:** The number of ways to arrange $n$ distinct items is $n!$.
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### a) No additional restrictions
3. Total tortillas: $2 + 4 = 6$.
4. Number of ways to arrange all 6 distinct tortillas is $$6! = 720.$$
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### b) The 2 meat tortillas must be together
5. Treat the 2 meat tortillas as a single block. Then we have this block + 4 vegetable tortillas = 5 items.
6. Number of ways to arrange these 5 items is $$5! = 120.$$
7. Inside the meat block, the 2 meat tortillas can be arranged in $$2! = 2$$ ways.
8. Total arrangements = $$5! \times 2! = 120 \times 2 = 240.$$
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### c) The 4 vegetable tortillas must be together
9. Treat the 4 vegetable tortillas as a single block. Then we have this block + 2 meat tortillas = 3 items.
10. Number of ways to arrange these 3 items is $$3! = 6.$$
11. Inside the vegetable block, the 4 tortillas can be arranged in $$4! = 24$$ ways.
12. Total arrangements = $$3! \times 4! = 6 \times 24 = 144.$$
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### d) The 2 meat tortillas must be at the beginning and end of the row
13. The row has 6 positions: positions 1 and 6 must be meat tortillas.
14. Number of ways to arrange 2 meat tortillas in positions 1 and 6 is $$2! = 2.$$
15. The 4 vegetable tortillas fill positions 2, 3, 4, 5 and can be arranged in $$4! = 24$$ ways.
16. Total arrangements = $$2! \times 4! = 2 \times 24 = 48.$$
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### e) The 2 meat tortillas must be together and the 4 vegetable tortillas must be together
17. Treat the 2 meat tortillas as one block and the 4 vegetable tortillas as another block. Now we have 2 blocks to arrange.
18. Number of ways to arrange these 2 blocks is $$2! = 2.$$
19. Inside the meat block, 2 tortillas can be arranged in $$2! = 2$$ ways.
20. Inside the vegetable block, 4 tortillas can be arranged in $$4! = 24$$ ways.
21. Total arrangements = $$2! \times 2! \times 4! = 2 \times 2 \times 24 = 96.$$
**Final answers:**
- a) 720
- b) 240
- c) 144
- d) 48
- e) 96