Question

Barbara can travel 3200m in 24 minutes, how far can she walk in 3 minutes?

Answer 1

Hint: To solve the above type of question we will use the speed distance time method, we will first find out the speed of Barbara and then multiply it with the amount of time that has been mentioned to get the desired output as to how much can she walk in 3 minutes.

Complete step by step solution:
The information that has been defined is the distance that Barbara travels and the amount of time taken by her to complete that distance which is,
Distance = d = 3200m
Time taken = t = 24 minutes
Now to calculate the speed of Barbara we will divide the distance (d) by time(t) which is the formula of speed and with this we will get the speed i.e.
\[\begin{align}
  & \text{speed}=\dfrac{\text{distance}}{\text{time}} \\
 & \Rightarrow \text{speed}=\dfrac{\text{d}}{\text{t}} \\
 & \Rightarrow \text{speed}=\dfrac{3200}{24} \\
 & \Rightarrow \text{speed}=\dfrac{(3200)(60)}{24(1000)} \\
 & \Rightarrow \text{speed}=8\text{ km/hr} \\
\end{align}\]
So now we have calculated the speed of Barbara, we can use this speed to calculate the distance she took in 3 minutes.
For this first we are going to convert minutes into hours as the speed that was taken out is in km/hr
So, to find the distance we will have to convert the time from minutes to hours.
To convert minutes to hours, we are going to divide the time by 60 to convert it into hours and hence we got,
\[\begin{align}
  & \text{time taken = }\dfrac{3}{60} \\
 & \Rightarrow \text{time taken}=\dfrac{1}{20}\text{hrs} \\
\end{align}\]
Now that we have calculated time in hours, we are going to multiply it with speed of Barbara to calculate the distance travelled by her in that amount of time and so we get,
\[\begin{align}
  & \text{distance travelled by Barbara(d1) = }(8)(\dfrac{1}{20}) \\
 & \Rightarrow \text{d1=}\dfrac{2}{5}\text{km} \\
 & \Rightarrow \text{d1=}\dfrac{2}{5}(1000)\text{m} \\
 & \Rightarrow \text{d1=}400\text{m} \\
\end{align}\]
Therefore, we can tell that the distance travelled by Barbara is equal to 400m in 3 minutes.

Note:
The general mistake that is done is that the units of distance and time are not checked due to which the correct answer is not found. So, to find the correct answer always check the units of the variables that you are taking and then change every other unit to the one you have taken as base unit, just like in the above question, we took the base unit as km and hour and then calculated with respect to them so as to make the calculation easier and wrote the final answer by changing it to the unit required by the question i.e. to metre.