Two trains leave from a cityi at 9:30 A.M and 10:00 A.M. and travel at 60kmph and 70 kmph resp. How many km from the city will two trains be together?
2007-07-02 06:34:35 · 5 answers · asked by plasmalightwave 1 in Science & Mathematics ➔ Mathematics
Let's say they meet at a time T measured from 9:30.
Then 60*T = 70*(T - 1/2)
T = 3.5 h
So distance of each = 60*3.5 = 210 km
2007-07-02 06:41:12 · answer #1 · answered by Dr D 7 · 1⤊ 0⤋
Let T = no. of hours travel
60kmph * (T + 1/2) = 70kmph * T
60kmphT + 30kmph = 70kmphT
30kmph = 70kmphT - 60kmphT
30kmph = 10kmphT
30kmph / 10kmph = T
3 = T
1st train travel distance = 60kmph * (3 + 1/2)
1st train travel distance = 60kmph * 3 1/2
1st train travel distance = 210km
2nd train travel distance = 70kmph * 3
2nd train travel distance = 210km
Answer is 210 kilometers.
2007-07-06 00:19:16 · answer #2 · answered by Jun Agruda 7 · 2⤊ 0⤋
Let t = time slower train travels
Then t-.5 = time faster train travels
So 60t = 70(t-.5) = 70t - 35
-10t = -35 --> t = 3.5
So 60*3.5 = =210 km = distance traveled by slow train
and, 70(3) = 210 km = distance traveled by faster train
2007-07-02 07:01:54 · answer #3 · answered by ironduke8159 7 · 0⤊ 0⤋
⦠time of #1 S/60 = time of #2 S/70 +(10:00 –9:30),
hence S/60 = S/70 +0.5; hence 7*S =6*S +210, hence S=210;
2007-07-02 06:51:06 · answer #4 · answered by Anonymous · 0⤊ 0⤋
Everyone above me has it right, but consider it this way:
At 10:00, the train that left at 9:30 is 30k away (0.5h*60k/h).
The train going 70kph, in one hour, will gain (70k-60k)=10k on the train going 60kph.
How long does it take the second train to make up 30k? 3 hours.
How far does the second train go in 3 hours? 210k.
2007-07-02 08:20:27 · answer #5 · answered by cdmillstx 3 · 0⤊ 0⤋