Set 14: Quadratic Equations (Intermediate)

Explanation

Answer: A

The stopping distance $d$ (in feet) of a car is modeled by $d(v) = 0.05v^2 + v$ , where $v$ is speed in mph. What is the stopping distance at 60 mph?

240 ft

✓ Correct

180 ft

300 ft

120 ft

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Substitute $v=60$ into the model. 1. $d(60) = 0.05(60)^2 + 60$ . 2. $d(60) = 0.05(3600) + 60$ . 3. $d(60) = 180 + 60 = 240$ feet. Choice B is incorrect. Choice C is incorrect. Choice D is incorrect.

Key Steps:

•

The correct answer is 240 ft

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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