Speed limit sign in Canada shows 70 km/h. Determine the speed in miles per hour: (Round to the nearest tenth) mph Nonc the Jnsiers correct: 42.8 mph 112.7 mph Question 33 How many hours does it take to travel 347 miles at a speed of 57 miles per hour? Round your answer to the nearest tenth: 0 hours 6.1 hours Faa U _ @ P1 32 hour hours
The Correct Answer and Explanation is:
Part 1: Convert 70 km/h to mph
To convert kilometers per hour (km/h) to miles per hour (mph), use the conversion factor:
1 kilometer = 0.621371 miles
So: 70 km/h×0.621371=43.49597 mph70 \, \text{km/h} \times 0.621371 = 43.49597 \, \text{mph}70km/h×0.621371=43.49597mph
Rounded to the nearest tenth: 43.5 mph\boxed{43.5 \, \text{mph}}43.5mph
Answer: 43.5 mph (None of the listed answers are correct if only 42.8 and 112.7 are given)
Part 2: Time = Distance ÷ Speed
We are given:
- Distance = 347 miles
- Speed = 57 mph
Using the formula: Time=34757=6.0877 hours\text{Time} = \frac{347}{57} = 6.0877 \, \text{hours}Time=57347=6.0877hours
Rounded to the nearest tenth: 6.1 hours\boxed{6.1 \, \text{hours}}6.1hours
Explanation
To solve real-life problems involving speed and distance, two fundamental unit conversions and formulas are often applied: converting between kilometers and miles, and using the formula for time, which is distance divided by speed.
In the first part, the speed limit in Canada is posted in kilometers per hour, but if you’re familiar with miles per hour, it’s helpful to convert it. Since 1 kilometer equals about 0.621371 miles, multiplying 70 km/h by that value gives us approximately 43.5 mph. This helps travelers from countries using the imperial system understand local speed limits without confusion. If only 42.8 mph and 112.7 mph are provided as choices, neither is correct, since the accurate result is closer to 43.5 mph.
In the second part, calculating the time it takes to travel a given distance at a certain speed involves the basic formula: Time=DistanceSpeed\text{Time} = \frac{\text{Distance}}{\text{Speed}}Time=SpeedDistance
So for 347 miles at 57 mph, dividing 347 by 57 gives about 6.1 hours. This means it would take just over six hours to complete that journey at constant speed, assuming no breaks or delays.
These kinds of conversions and calculations are not only common in travel scenarios but also in science and engineering where consistent units and precise time management are critical. Mastering them is essential for accurate problem-solving and planning.
