A and B are two points 90 km apart on a highway. Two cars start from A and B at the same time. If they move in the same direction they meet in 9 hours. But if the move in the opposite direction, they meet in 9/4 hours, find their speeds.
Answers
Answer:
10
Step-by-step explanation:90/9=10
Step-by-step explanation:
Given:-
A and B are two points 90 km apart on a highway. Two cars start from A and B at the same time. If they move in the same direction they meet in 9 hours. But if the move in the opposite direction, they meet in 9/4 hours.
To find:-
Find their speeds.
Solution:-
Given two points are A and B
Let The speeds of two cars be X km/hr and
Y km/hr
The distance between two points = 90 km
Case -1:-
They meet in 9 hours if they move in the same direction
Their relatively speed = Difference between their speeds
=>X-Y km/hr
we have
Speed = X-Y km/hr,
Distance = 90 km
Time = 9 hours
Distance = Speed ×Time
=>90 = (X-Y)×9
=>X-Y=90/9
X-Y = 10 ------------(1)
Case -2:-
They meet in 9/4 hours if they move in opposite direction
Their relatively speed = Sum of their speeds
=>X+Y km/hr
W e have,
Speed = X+Y km/hr
Distance = 90 km
Time = 9/4 hours
Distance = Speed ×Time
=>90 = (X+Y)×(9/4)
=>90×(4/9) = X+Y
=>10×4 = X+Y
X+Y = 40 ----------(2)
On solving (1)&(2)
X + Y = 40
X - Y = 10
(+)
____________
2X + 0 = 50
____________
=>2X = 50
=>X = 50/2
=>X = 25
On Substituting the value of X in (1) then
25-Y = 10
=>Y = 25-10
=>Y = 15
The values of X= 25 and Y = 15
Answer:-
The speed of one car = 25 km/hr
The speed of another car = 15 km/hr
Used formulae:-
- Distance = Speed ×Time
- If two objects move in opposite direction then their relatively speed is the sum of their speeds.
- If two objects move in same direction then their relatively speed is the difference between their speeds.