GMAT Inequalities: What is the maximum number of balls…
Question
7x + 6y ≤ 38,000 4x + 5y ≤ 28,000 A manufacturer wants to produce x balls and y boxes. Resource constraints require that x and y satisfy the inequalities shown. What is the maximum number of balls and boxes combined that can be produced given the resource constraints?
- 5,000
- 6,000
- 7,000
- 8,000
- 10,000
Topics: inequalities
Solution
Step 1
We first name the variables to match the question.
x = number of balls y = number of boxes
Step 2
We sum the two resource constraints "7x + 6y ≤ 38000" and "4x + 5y ≤ 28000", applying Adding Two Inequalities.
7x + 6y ≤ 38000 4x + 5y ≤ 28000 11x + 11y ≤ 66000
Step 3
We divide both sides of the combined inequality by 11, which is positive, so the inequality direction stays the same according to Multiplying/Dividing Inequalities by Positive.
(11x+11y)/11 ≤ 66000/11 x + y ≤ 6000
Step 4
We verify that the bound is attainable by finding values that satisfy both original constraints.
7 × 2000 + 6 × 4000 = 38000 4 × 2000 + 5 × 4000 = 28000 x + y = 2000 + 4000 = 6000
Answer
6,000 (B)
