Question

A train covers a distance 720 in 18 hours. How much time will the train require to cover a distance of 200 km with same speed ?

Answer 1

Answer :

• 5 hours

Given :

• The distance of train covered 720km in 18 hour.

To Find :

• How much time will the train require to cover a distance of 200 km with same speed.

Note :

• We can find the answer by using 3 methods, all the methods are shown below.

Solution :

First method :

Let x and y represent time and distance respectively.

• Now, let us prepare the following table -

$\small\boxed{\begin{array}{c|c|c} \bf\underline{ \: \: \: \: \: Time\ (x) \: \: \: \: \: }& \tt \underline{ \: \: 18\ (x_1) \: \: }& \tt \underline{ \: \: \: \: \: \: \: x_2 \: \: \: \: \: \: }\\ \bf Distance\ (y)\ & \tt 720\ (y_1) & \tt 200\ (y_2)\\\end{array}}$

Here, more distance, more time. Therefore, it is direct proportion.

$\tt \therefore \: \: \: \: \: \: \: \dfrac{x_1}{y_1} = \dfrac{x_2}{y_2 } \\ \\ \tt \implies \: \dfrac{18}{720} = \dfrac{x_2}{200} \\ \\ \tt \implies x_2 = \dfrac{18}{720} \times200 \\ \\ = \bf \: 5$

Therefore, The train will require 5 hours to cover 200 km.

Second method :

To cover 720 km, time required 18 hours

$\small \rm \therefore To \: cover \: 1 km, \: time \: required \: \dfrac{18}{720} \: hours$

$\small \rm \therefore To \: cover \: 200 km, \: time \: required \: \bigg( \dfrac{18}{720} \times200 \bigg) \: hours \\ \\ = \bf 5 \: hours$

Third method :

Since less time will be required to cover less distance, therefore, it is direct proportion.

• Here, we are to find time and less time will be required.

$\rm \therefore Time \: required =18×\dfrac{200}{720} \\ \bf = 5 \: hours$

(For less time, we should multiply by lesser ratio i.e. $\dfrac{200}{720}$ which is less than 1).