Question

. An express train takes 30 minutes less for a journey of 400 km
if its speed is increased by 8km/ hr.find its usual speed​

Answer 1

Answer:

Given : An express train takes 30 minutes less for a journey of 440 km, if its usual speed is increased by 8 km/hr.

To find : Its usual speed?

Solution :

Expressing time in hours,

Difference in time= 0.5 hour

Let usual speed be x

T = 1/2

According to question,

440

440 = 0.5

x+8

440(x+8)x= 0.5x(x+8)

440 x 8 = 0.5(x²) + 4x

0.5(x²) + 4x 3520 = 0

(x²)+8x 70400

(x²)+88x 80x 7040 = 0

(x+88) (x − 80) = 0

x = 80

Therefore, The usual speed is 80 kmph.

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