6
algebra

A plane flies 1200 miles in 3 hours with the wind. Against the wind, it takes 4 hours. What is the speed of the wind?

A

100

B

25

C

350

D

50

Correct Answer: D

Choice Ahoice C is the correct answer.

  1. Speeds: With wind = 1200/3=4001200/3 = 400. Against = 1200/4=3001200/4 = 300.
  2. Equations: p+w=400p + w = 400, p−w=300p - w = 300.
  3. Subtract: (p+w)−(p−w)=400−300→2w=100(p+w) - (p-w) = 400 - 300 \rightarrow 2w = 100
  4. Divide by 2: w=50w = 50
  5. Verify: Plane 350. 350+50=400350+50=400, 350−50=300350-50=300 ✓

Choice Ahoice D is incorrect because this is the plane's speed.

Choice Ahoice B is incorrect because calculation error.

Choice Ahoice D is incorrect because calculation error.

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