Question

If a runner maintains a constant speed of 12 km/hr, how long will it take to complete a marathon race of 26.2 miles(assuming that 1 km = .62 miles)?

Answer 1

At 12 km/hr, how long does it take to go 26.2 miles?

We know that distance= rate*time

So we know that 26.2 = 12*time

We can now see that time= 26.1/12= 3.52h

Answer 2

Given,

Constant speed of a runner = 12 km/h.

1 km = 0.62 miles.

To find,

The time he will take to complete a race of 26.2 miles.

Solution,

Here, the speed is in km/h but the total distance to be covered is given in miles. So first, we need to convert the speed into similar units as that of the distance.

As it is given 1 km = 0.62 miles,

⇒ 12 km/h = 12×0.62 mph

⇒ 12 km/h = 7.44 mph

So, speed s = 7.44 mph, and,

the distance to be covered is d = 26.2 miles.

Now, applying the formula

$s=\frac{d}{t}$

Where,

s = speed

d = distance, and,

t = time.

Substituting the respective values, we get,

$7.44 =\frac{26.2}{t}$

Rearranging and simplifying,

$t=\frac{26.2}{7.44} h$

⇒ t = 3.52 h

Therefore, the time taken by the runner to complete a marathon race of 26.2 miles will be 3.52 h.