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November 13th, 2018, 11:30 PM   #1
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what time did Kamal reach City A?

Kamal left for the city A from City B at 5:20 Am. He traveled at a speed of 80 kmph for 4 hours 15 min. After that, the speed was reduced to 60 km/hr. If the distance between two cities is 350 km, at what time did Kamal reach City A.


In the time: 4hr15min from B, distance travelled by Kamal is 340 km.
After distance is 340km, speed is reduced to 60 kmph. Still he has to travel 10km.
Time taken by Kamal for 10 km after speed reduced to 60 kmph = 10/60 = 0.166 hr
Total Time is 5:20 Am + 4hr15min + 0.166 hr.

But answer is 9:45 AM

Last edited by Ganesh Ujwal; November 13th, 2018 at 11:35 PM.
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November 13th, 2018, 11:48 PM   #2
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during the portion of the trip at 80 km/hr Kamal travels

$d_1 = 4.25\cdot 80 = 340~km$

he travels the remaining 10 km at 60 km/hr and this takes

$\dfrac{10}{60} = \dfrac 1 6 ~hr = 10~min$

his total time is thus 4 hrs and 25 min

If he leaves at 5:20 AM he arrives at 9:45 AM
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November 14th, 2018, 08:51 AM   #3
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Your diagram is a mess!

B(@80)....................>(17/4 hours)(@60)...............>A(t hours)

80*(17/4) + 60*(t - 17/4) = 350 ; solve for t:
t = 53/12 = total travelling time
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