2

Set 16: Linear Inequalities

Explanation

Answer: A

A bakery sells cakes for $25each. The ingredients cost \8 per cake, and the monthly rent is $600. How many cakes $$c must be sold to make a profit of at least \1000 this month?

A.

c95c \geq 95

✓ Correct
B.

c64c \geq 64

C.

c32c \geq 32

D.

25c8c600100025c - 8c - 600 \geq 1000

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Profit is calculated as Revenue minus Costs. 1. Revenue: $25percake(25per cake (25 c) 2. Variable Cost: \8per cake (8 c$$) 3. Fixed Cost: \$$600rent 4. Profit Equation: Profit = Revenue - Variable Cost - Fixed Cost 5. Inequality: $$(25 c - 8 c) - 600 \geq 1000 6. Simplify: 17c600100017c - 600 \geq 1000 7. Add 600: 17c160017c \geq 1600 8. Divide by 17: c94.11...c \geq 94.11... 9. Round up: Since you can't sell a fraction of a cake, c95c \geq 95 Strategic Tip: Net profit per unit is (Selling Price - Cost per unit). Total Profit = (Net per unit × Quantity) - Fixed Costs. Choice B is incorrect because it ignores the variable cost of ingredients (25c600100025c - 600 \geq 1000). Choice C is incorrect because it ignores the rent (17c100017c \geq 1000). Choice D is incorrect because while the setup is correct, Choice A is the solved answer, and D is just the setup (though mathematically valid, A is the explicit solution requested by "How many cakes..."). Correction: Choice D is the setup, but A is the solution. The question asks "How many cakes", so A is the answer.

Key Steps:

The correct answer is c95c \geq 95

Why others are wrong:
B: Choice B is incorrect and may result from a calculation error.
C: Choice C is incorrect and may result from a calculation error.
D: Choice D is incorrect and may result from a calculation error.

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