Question

a car covers the distance of 648 km. the no. of hours taken for the journey is one half the no. represent in the speed in kilometre per hour find the time taken to cover the distance ​

Answer 1

$\bold{\underline{\underline{Answer:}}}$

Time taken to cover the distance is 18 hrs.

$\bold{\underline{\underline{Step\:by\:step\:explanation:}}}$

Given :

• A car covers the distance of 648 km.
• The number of hours taken for the journey is one half the number representing the speed in kilometre per hour

To find :

• Time taken to cover the distance.

Solution :

Let the speed of the car be x km/hr.

$\bold{\underline{\underline{As\:per\:the\:given\:condition:}}}$

• The number of hours taken for the journey is one half the number representing the speed in kilometre per hour

•°• Hours needed = $\bold{\dfrac{x}{2}}$ hrs.

We have :-

• Speed = x km/hr
• Distance (D) = 648 km
• Time = $\bold{\dfrac{x}{2}}$

So we can use the formula for speed and thereby solve the question.

Formula :

$\bold{\large{\boxed{\red{\sf{Speed\:=\:{\dfrac{Distance}{Time}}}}}}}$

Block in the values,

$\rightarrow$$\bold{x= 648\:÷\:{\dfrac{x}{2}}}$

$\rightarrow$$\bold{x= 648\:\times\:{\dfrac{2}{x}}}$

$\rightarrow$$\bold{x={\dfrac{1296}{x}}}$

Cross multiplying,

$\rightarrow$$\bold{x^2=1296}$

$\rightarrow$$\bold{x={\sqrt{1296}}}$

$\rightarrow$$\bold{x=36}$

•°• Speed = x = 36 km/hr.

Time = $\bold{\dfrac{x}{2}}$

Substitute x = 36,

Time = $\bold{\dfrac{36}{2}}$

•°• Time = 18 hours.

•°• The car will cover 648 km in 18 hours.

Answer 2

SOLUTION:-

════════════

Given:

A car the distance of 648km the number of hours taken for the journey is one half the number represent in the speed in Km/hrs.

To find:

══════

The time taken to cover the distance.

Explanation:

══════════

•Formula: Speed

$Speed = \frac{Distance}{Time}$

•Formula: Time

$Time = \frac{Distance}{Speed}$

•Formula: Distance

$Distance = Speed \: \times Time$

According to the question:

Assume the Time taken be R hours.

We have,

• Speed= 2R km/hrs
• Distance= 648km

Using Formula: Time

$= > Time = \frac{Distance}{Speed}$

So,

$R = \frac{648}{2R} \\ \\ [cross \: multiplication] \\ = > 2 {R}^{2} = 648 \\ \\ = > {R}^{2} = \frac{648}{2} \\ \\ = > {R}^{2} = 324 \\ \\ = > R = \sqrt{324} \\ \\ = > R = 18 \: hours$

Thus,

The time taken to cover's distance= 18 hours.

:)