A car is traveling 70 km in 45 minutes. How many miles an hour is the car traveling? The conversion factor you will need for this question is: 1 mile = 1.60934 km About 60 miles per hour About 52 miles per hour About 50 miles per hour About 58 miles per hour
The Correct Answer and Explanation is:
Correct choice: About 58 miles per hour
Why that’s the right answer (about 300 words)
To compare the car’s speed with the familiar “miles per hour” (mph) scale, we must first express its speed in kilometers per hour (km/h) and then convert those kilometers to miles.
1 Find the time in hours
The trip lasts 45 minutes.
Because 60 minutes make one hour: 45 min = 4560 h = 0.75 h45\text{ min}\;=\;\frac{45}{60}\text{ h}\;=\;0.75\text{ h}
2 Compute the speed in km/h
Speed equals distance divided by time: speed = 70 km0.75 h = 93.3‾ km/h\text{speed} \;=\;\frac{70\text{ km}}{0.75\text{ h}}\;=\;93.\overline{3}\text{ km/h}
3 Convert kilometers per hour to miles per hour
The problem supplies the conversion 1 mile=1.60934 km1\text{ mile}=1.60934\text{ km}.
To get miles from kilometers, divide by 1.60934: 93.3‾ km/h × 1 mile1.60934 km ≈ 57.94 mph93.\overline{3}\text{ km/h}\;\times\;\frac{1\text{ mile}}{1.60934\text{ km}} \;\approx\;57.94\text{ mph}
Rounded sensibly, that is about 58 mph.
4 Check against the answer choices
- About 60 mph: a little high—would require ~96 km/h.
- About 52 mph: too low—corresponds to ~84 km/h.
- About 50 mph: even lower—~80 km/h.
- About 58 mph: matches the 57.9 mph we computed.
Therefore, “About 58 miles per hour” is the only option consistent with the calculation.
5 Why the rounding makes sense
Every real-world speedometer fluctuates slightly, and the given data (70 km in 45 min) is likely rounded to the nearest kilometer and minute. Presenting the answer to the nearest whole mile per hour preserves realistic precision without implying greater accuracy than the input justifies.
6 Rule-of-thumb shortcut (optional)
If you ever need a quick estimate, remember that 100 km/h ≈ 62 mph. Since 93 km/h is a bit less than 100 km/h, its mph value must be slightly below 62 mph—again pointing to the upper-50s.
With the formal calculation and the mental check agreeing, we can be confident that the car’s speed is about 58 miles per hour.
