Question

A car left 30 minutes later than the scheduled time in order to reach its destination 150km away in time it has to increase its speed by 25km/hr from its usual speed. Find its usual speed ​

Answer 1

Answer:

Step-by-step explanation:

Let the usual speed of the car be X km/hr

Distance travelled =150km.

Time taken to travel (t¹)= 150/X

Also,

The speed increased = X +25 km/hr

So, time taken = (t²)=150/X + 25

Now,

According to the question ,we have,

t¹ - t² =30/60

150/X - 150/X + 25 = 1/2

150( X +25) - 150(X) / X(X+25)= 1/2

150X+3750 -150 X/ X² + 25X= 1/2

3750/X² + 25X= 1/2

2(3750) = 1(X² + 25X)

7500 = X² + 25X

X² + 25X - 7500=0

X² + 100X - 75 X- 7500=0

X (X + 100) -75( X +100)

(X+ 100)(X -75)

So, X = -100(speed can't be negative

.hence neglected)

or

X = 75

So , usual Speed = 75 km/hr

Hope it helps.