Question

A man runs from a place A to a place B in 1 hour 30 minutes. If the distance between the two places is 6km, find his speed.

Answer 1

Hint: First convert the time taken by the man in hours by dividing the minutes part by 60. Now substitute the value of distance and time in the formula $Speed = \dfrac{{Distance}}{{Time}}$. After that do the calculation to get the speed of the man.

Complete step-by-step solution:
Given: - Distance travelled by the man = 6 km
Time is taken by the car = 1 hour 30 minutes
Let the speed of the man be $S$.
To find the speed of the man, the time taken 1 hour 30 minutes must be converted into hours.
To convert the minutes in hours, divide the minutes by 60,
$ \Rightarrow 1 + \dfrac{{30}}{{60}}$
Cancel out the common factor,
$ \Rightarrow 1 + \dfrac{1}{2}$
Take LCM and add then add the number in the numerator,
$ \Rightarrow \dfrac{3}{2}$
So, the time taken by the man is $\dfrac{3}{2}$ hours.
The average speed of an object can be defined as the total distance travelled by it in a particular interval of time. It can be calculated by dividing the total distance travelled by the total time taken.
The formula to calculate the speed is,
$Speed = \dfrac{{Distance}}{{Time}}$
Substitute the values of distance and time,
$ \Rightarrow S = \dfrac{6}{{\dfrac{3}{2}}}$
Move 2 to the numerator,
$ \Rightarrow S = \dfrac{{6 \times 2}}{3}$
Cancel out the common factors,
$S = 2 \times 2$
Multiply the terms,
$S = 4$km/h

Hence, the speed of the man is 4 km/h.

Note: The students are likely to make mistakes in questions which have units in a different form. Students are advised to use common conversions first to convert all the values in the same unit and then do calculations. Then change back the units into the original form.