Excluding stoppages, the speed of a train is 40 km/h and including sto

Question

Excluding stoppages, the speed of a train is 40 km/h and including stoppage, it is 32 km/h. For how many minutes does the train stop per hour ?

(A) 10
(B) 12
(C) 15
(D) 18
(E) 20

CrackverbalGMAT · Accepted Answer

Without stoppage he travels 40 km in 60 minutes. Therefore he travels 1 km every 60/40 = 3/2 minutes

With stoppage he travels 32 km in 1 hour.

To travel 32 km, he requires 32 * (3/2) = 48 minutes

Therefore his stoppage time is 60 - 48 = 12 minutes

Option B

Arun Kumar

imeanup · Answer

\frac{S_{excluding}}{S_{including}}=\frac{40}{32}=\frac{5}{4}

\frac{T_{excluding}}{T_{including}} = \frac{4}{5}

Refer to the image for more information.

Ans B

Nik11 · Answer

I got the point of the above-mentioned methods, but I offer an alternative from my point of view much more intuitive.

LCM for a smart distance ----> 160km
At 40 km/h this distance is covered in 4 hours
At 32 km/h is covered in 5 hours
Good 1 hour of difference, hence (1/5) * 60 min is time per min spent in stoppages ---> 12 minutes

Budhaditya_Saha · Answer

Please guide me where am I getting this incorrectly?  Bunuel

I assumed the total distance travelled by the trains be x.
Now the time taken to traverse the distance without stoppages be t
Lets say the time for stoppage be T.
Thus the total time taken including stoppages is t+T.

Now since the distance traversed is x so, x= 40*t
And considering the stoppages we get x = 32(t+T)

Thus 40*t = 32*(t+T)
Thus 8t=32T
thus, T=(1/4)*t in hrs.

to convert it into mins we multiply by 60, Thus T = 15t

Now t=1, as we need the stoppage time  per hour.  
Hence T=15*1 = 15mins.

Answer C

Bunuel · Answer

Budhaditya_Saha · Answer

Thank You!  Bunuel

Posted from my mobile device

bumpbot · Answer

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Excluding stoppages, the speed of a train is 40 km/h and including sto

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Excluding stoppages, the speed of a train is 40 km/h and including sto

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