Two places A and B are 80km apart from each other on a highway. a car starts from A and another from B at the same time. If they move in the same direction, they meet in 8 hours and if they move in opposite directions they meet in 1 hour and 20 minutes. find the speed of the cars
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Answers
Answered by
425
Hi,
Let the speed of the first car which
starts from A = x km /hr
Speed of the second car which starts
from B = y km / hr
We know that,
______________________
Time = distance / speed
______________________
Distance between two places A and
B are 80km
d = 80 km
i ) if the cars move in same direction
Relative speed of them = ( x + y )
km/hr
Time = 8hr
d = 80km
8 = 80 / ( x + y )
x + y = 80 / 8
x + y = 10 ------( 1 )
ii ) if two cars moving opposite
direction,
Relative speed = ( x - y ) km / hr
Time = 1 hr 20 minutes
= ( 1 + 20 / 60 ) hr
= ( 80/60)
= 4/3 hr
d = 80km
4/3 = 80 / ( x -y )
x -y = ( 80 × 3 ) / 4
x - y = 60-----( 2 )
Add ( 1 ) and ( 2 ) , we get
2x = 70
x = 35
Put x = 35 in ( 1 ) we get ,
y = 25
Therefore ,
Speed of the first car = x = 35km/hr
Speed of the second car = 25km /hr
I hope this helps you.
:)
Let the speed of the first car which
starts from A = x km /hr
Speed of the second car which starts
from B = y km / hr
We know that,
______________________
Time = distance / speed
______________________
Distance between two places A and
B are 80km
d = 80 km
i ) if the cars move in same direction
Relative speed of them = ( x + y )
km/hr
Time = 8hr
d = 80km
8 = 80 / ( x + y )
x + y = 80 / 8
x + y = 10 ------( 1 )
ii ) if two cars moving opposite
direction,
Relative speed = ( x - y ) km / hr
Time = 1 hr 20 minutes
= ( 1 + 20 / 60 ) hr
= ( 80/60)
= 4/3 hr
d = 80km
4/3 = 80 / ( x -y )
x -y = ( 80 × 3 ) / 4
x - y = 60-----( 2 )
Add ( 1 ) and ( 2 ) , we get
2x = 70
x = 35
Put x = 35 in ( 1 ) we get ,
y = 25
Therefore ,
Speed of the first car = x = 35km/hr
Speed of the second car = 25km /hr
I hope this helps you.
:)
Answered by
156
let the speed of the car at A be x km/ h
and the speed of the car at B be y km/ h
case 1 8x-8y=80
x-y=10
case 2 4/3x + 4/3y = 80
x+y = 60
on solving x = 35 and y = 25
hence, speed of the cars at A and B are 35 km/h and 25 km/h respectively.
i hope this helps you
plz mark it as brainlyest answer
and the speed of the car at B be y km/ h
case 1 8x-8y=80
x-y=10
case 2 4/3x + 4/3y = 80
x+y = 60
on solving x = 35 and y = 25
hence, speed of the cars at A and B are 35 km/h and 25 km/h respectively.
i hope this helps you
plz mark it as brainlyest answer
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