1. anonymous

1 km =0.625 miles 1s=1/3600 hour

2. steve816

I got 67,068 mile/hour, can someone check my answer?

3. jim_thompson5910

1 km = 0.621371 mi (approx) 1 hr = 3600 seconds $\Large \frac{30 \text{ km}}{1 \text{ sec}} \times \frac{0.621371 \text{ mi}}{1 \text{ km}} \times \frac{3600 \text{ sec}}{1 \text{ hr}}$ Notice how I set this up to where the "km" units cancel (one "km" unit up top, the other "km" down in the denominator. They divide to 1) $\Large \frac{30 \cancel{\text{ km}}}{1 \text{ sec}} \times \frac{0.621371 \text{ mi}}{1 \cancel{\text{ km}}} \times \frac{3600 \text{ sec}}{1 \text{ hr}}$ Also, the "sec" units cancel as well for the same reason as the "km" units cancelling $\Large \frac{30 \text{ km}}{1 \cancel{\text{ sec}}} \times \frac{0.621371 \text{ mi}}{1 \text{ km}} \times \frac{3600 \cancel{\text{ sec}}}{1 \text{ hr}}$

4. jim_thompson5910

I got 67,068 mile/hour, can someone check my answer? I'm getting a slightly larger number @steve816

5. steve816

I think it's because I rounded the miles to 0.62. But I understand it now! Thanks for the help!

6. jim_thompson5910

no problem