Jack and Dan competed against each other in a round of running. They both ran a kilometer. Jack took about 8 minutes to finish the race while Dan took around 5. What’s their speed in kilometers per hour? Imagine if they ran for another 3 hours at half their original speed. How far would they go and who would go farther?
To find speed, we must take the distance and divide it by the time. In the case for Jack, it would be: 1 (kilometers) ÷ 8 (minutes). Do the math and you would get 0.125, so Jack’s speed is 0.125 km in a minute. But we want km/h. We just need to convert it. To convert it, basically multiply by 60 because an hour is 60 minutes, so 0.125 (km per minute) x 60 (number of minutes in an hour) and you would get 7.5 km/h. That is Jack’s speed in kilometers per hour.
Let’s quickly find Dan’s speed:
1 km (how far Dan ran) ÷ 5 minutes (how long he took) = 0.2 km/minute (his speed)
0.2 km/minute x 60 (number of minutes in an hour) = 12 km/h (his speed converted from km/minute into km/h)
Now how far would they go if they ran for another 3 hours half their original speed?
First I would find their new speed. That’s easy, just divide their original speed by two.
Jack’s new speed: 7.5 ÷ 2 = 3.75 km/h
Dan’s new speed: 12 ÷ 2 = 6 km/h
To find out how far they would go, we need to multiply their speed by how long they would run.
For Jack, 3.75 km/h (his speed) times 3 (time of running) would find out his distance. It’s 11.25 km. In Dan’s case, his distance would be 18 km.
So if they both ran for another 3 hours at half their original speed, Jack would run 11.25 kilometers and Dan would run 18 kilometers. Who ran farther? You know how to do this one, it’s Dan because 18 is obviously bigger than 11.25; just find the number that’s bigger.