Question

Sum and difference of the speeds of two cars are 70 km / hr & 30 km / hr respectively. In a race, if the car with more speed finished 3 minutes earlier than the other. The racing distance was equal to?​

Answer 1

LET US SUPPOSE THE VELOCITY OF TWO CARS ARE X AND Y RESPECTIVELY.

AND LET US ASSUME CAR X MOVES WITH MORE VELOCITY COMPARED TO Y.

SO,GIVEN

X+Y=70KMPH

X-Y=30KMPH

ADD BOTH THESE EQUATIONS

2X=100KMPH

X=50KMPH

X+Y=70

50+Y=70

Y=20KMPH

TIME TAKEN BY CAR X=A HOURS

TIME TAKEN BY CAR B=A+1/20 HOURS

TOTAL DISTANCE=VELOCITY×TIME TAKEN

CAR X

S=V×T

S=50×A

CAR Y

S=20×(A+1/20)

S=20×A + 1

WE KNOW THAT DISTANCES TRAVELLED BY THEM ARE EQUAL

SO,

50×A=20×A+1

30×A=1

A=1/30 HOURS

SUBSTITUTE THE VALUE OF A IN ONE OF THE EQUATION.

YOU WILL GET THE DISTANCE IS EQUAL TO 5/3 KM