Command of Evidence: Quantitative

SAT Reading and Writing· difficulty 5/5

Researchers studied four bridge designs subjected to identical wind loads. They measured maximum sway (cm) at two wind speeds: 30 mph and 60 mph. Design I, sway 4 cm at 30 mph, 9 cm at 60 mph; Design II, 6 cm at 30 mph, 24 cm at 60 mph; Design III, 5 cm at 30 mph, 11 cm at 60 mph; Design IV, 3 cm at 30 mph, 16 cm at 60 mph. The researchers argued that engineers should select bridges based on how sway <em>scales with wind speed</em>, not on low-wind sway alone. The data point most uniquely supporting this claim is ______

Which choice most logically completes the text using the data above?

  • A

    the average sway across all designs.

  • B

    Design I's lowest 30 mph sway of 4 cm.

  • C

    Design IV: lowest 30 mph sway (3 cm) but a much larger 60 mph sway (16 cm), versus Design I's modest 30→9 cm increase.

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  • D

    Design II's highest 60 mph sway of 24 cm.

Explanation

The claim is that selection by low-wind sway alone misleads—you must consider scaling with wind speed. Choice B uniquely demonstrates this: Design IV looks best at 30 mph but scales much worse to 60 mph than Design I, exactly the kind of misleading rank-reversal the researchers warn about.

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