Answer: Choice B
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Step-by-step explanation:
We'll use the following facts (either memorized or written on a reference sheet somewhere)
- 1000 m = 1 km
- 1 hr = 60 min
- 1 min = 60 sec
Each of those equations will form conversion factors to help us go from km/hr to m/s. Each conversion factor is a fraction connecting the two sides of the equation. Example: The equation 1000 m = 1 km forms the conversion factor of
In choice B, notice how the fractions are set up. The "km" units cancel when dividing. The same goes for the "hr" and "min" units.
Check out the screenshot below where I show this cancellation in action. The color-coding helps show how the terms pair up and cancel.
Choice A comes close to what choice B is saying, but we don't have the "min" units cancel. So choice A is eliminated as an answer.
Choices C and D are also eliminated because of the "75 km" in the denominator. It should be 1 km.