Question 855322: An athlete runs from A to B and back, at a speed of 10 kmph, while a second athlete simultaneously runs from B to A and back, at a speed of 15 kmph. If they cross each other for the first time 12 in min. after they start, then when will they meet each other for the second time.
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! An athlete runs from A to B and back, at a speed of 10 kmph,
while a second athlete simultaneously runs from B to A and back, at a speed of 15 kmph.
If they cross each other for the first time 12 in min. after they start, then when will they meet each other for the second time.
:
It may help if we find the distance from A to B
Each will cover a portion of the total dist in 12 min
12 min = .2 hrs
d = .2(10) + .2(15)
d = 2 + 3
d = 5 km from A to B
:
to meet again, they have to travel 3 + 2 + 5 = 10 km, twice as far so in 24 min
:
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Response to student question
"how the distance between A & B will be 5 Km as we we calculate the distance for 12 min. "
:
We know that both runners ran for 12 min. Since we are using km/hr, we change 12 min to 12/60 = .2 hrs
We can find the distance each ran by multiplying the time times the speed
1st runner .2 * 10 = 2 km
2nd runner .2 * 15 = 3 km
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the total is the dist from A to B, hence 5 km
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