Question

A car covers a distance of 240 km with some speed. If the speed is increased by 20 km/hr. It will cover the same distance in 2 hr. less find the speed of car​

Answer 1

Step-by-step explanation:

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Answer 2

Given:

Car travel distance with some speed for 240 km

Then it increases speed by 20 km/ hr and travels 240 km in two hours.

To Find:

the original speed of the car

Solution:

Let consider original speed of car s x km/hr

After incresing speed by 20 km/hr the speed will be ( 20 + x ) km/hr

As it is given that after incresing speed the car will cover distance in 2 hours less than original time so,

⇒ speed = distance / time

⇒ time T₁  = distance / speed

            T₁  = 240 / x

And,

            T₂ = 240 /  ( x + 20 )

            T₂ = 240 / ( x + 20 )

As we know car take 2 hours less with increased speed

Therefore,

T₁ - T₂ = $\frac{240}{x}$ - $\frac{240}{x + 20}$

2 = 240 ( x + 20 ) - 240x

2x .(x + 20) = 240x + 4800 - 240x

2x² + 40x - 4800 = 0

x² + 20x - 2400 = 0

x² + 60x - 40x - 2400 = 0

x ( x + 60 ) - 40 ( x + 60 ) = 0

( x + 60 ) . ( x - 40 ) = 0

x = 40 , x =  - 60

Speed can not be negative so x = - 60 is neglected

Hence, the original speed of the car is 40 km /hr.