Find the number of students in each room
38. Points A and B are 70 km apart on a highway. A car starts from A and
another car starts from B simultaneously. If they travel in the same
direction, they meet in 7 hours. But, if they travel towards each other
they meet in 1 hour. Find the speed of each car
Answers
Answered by
1
Step-by-step explanation:
When they travel in same direction, suppose
they meet when B travels for x m, then A will have travelled 70+x
m in the same time
Since, Speed =
Time
Distance
Speed of car at A =
7
x+70
And Speed of car at B =
7
x
And when they travel in the opposite direction, suppose they meet when A
travels for y m, then B will have travelled 70−y m in the same
time
Speed of car at A =
1
y
=y
And Speed of car at B =
1
70−y
=70−y
Equating the speeds of the cars in both the cases,
Speed of car at A,
7
x+70
=y
x+70=7y
=>x−7y=−70 --- (1)
Speed of car at B,
7
x
=70−y
=>x+7y=490 --- (2)
Adding equations 1 and 2, we get 2x=420=>x=210
So, Speed of car at A =
7
x+70
=
7
280
=40km/hr
Speed of car at B =
7
x
=
7
210
=30km/hr
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