Question

Q.6

The fast train takes 2 hour less to travel distance of
300km than the slow train whose speed is 5km/hr less than the the fast train !

Find the speed of fast train !

CBSE | Class 10

Answer 1

heya..!!!


let the speed slow train = x
then speed of fast train = (x + 5)

time = distance/speed

now,

300/x - 300/(x + 5) = 2

=> 300[x + 5 - x)]/x(x + 5) = 2

=> x(x + 5) = (5)300/2

=> x² + 5x = 750

=> x² + 30x - 25x - 750 = 0

=> x(x + 30) - 25(x + 30 = 0

=> (x - 25)(x + 30) = 0

=> x = 25 , - 30 [neglect]

hence the speed of faster train = (25 + 5)km/hr =30km/hr.


hope it's help you

Answer 2

HELLO DEAR,

LET THE SPEED OF SLOWER TRAIN BE (S)
AND FASTER TRAIN BE (S + 5)

NOW,

distance = time × speed

=> time = distance/speed

300/x - 300(x + 5) = 2


= > 300[ 1/x - 1/(x + 5)] = 2


=> (x + 5 - x) / (x² + 5x) = 1/150


=> 750 = x² + 5x

=> x² + 5x - 750

=> x² + 30x - 25x - 750 = 0

=> x(x + 30) - 25(x + 30) = 0

=> (x + 30)(x - 25) = 0

=> x = -30 , x = 25

x = -30[neglect]

x = 25



hence the speed of faster train = (25 + 5)km/hr =30km/hr.



I HOPE ITS HELP YOU DEAR,
THANKS