Aptitude - Time and Distance - Discussion

Suppose car speed is 'x' km/hr and speed of train is 50% higher than car speed,

i.e. [ x + 50/100x].

Hence [ x + 0.5x] = 1.5x.

i.e. 150/100x this is speed of car.

And what about that 12.5 min?

Let car complete distance of 75 km in time t with speed v kmhr

Distance = time x velocity

i.e. 75 km = t * v ------ equation 1

Train waste 12.5 min hence time required for train is t-12.5min

Convert 12.5 min in to hour = 12.5 ÷ 60 = 5 / 24.

i.e. time required for train is t- 5/24.

Speed of train is 50% more than car i.e. 3/2 v.

Distance = time x velocity

Now equation for train is 75 = (t - 5/24) (3 / 2 v) ---------- equation 2.

Now equate equations 1 and 2,

t x v = t - ( 5/24) (3/2 v).

After solving this equation we get,

t = 5 /8.

NOW put t= 5/8 value in equation 1 we get V = 120 i. e. Car speed.

Since the Car covered the half distance while train was halting, the speed of car becomes 75/2 * 60/12.5 = 180KM/hr

Now Train is 50% faster than car so train's speed should be 180 + 90 = 270 KM/hr

Hi @Mancy,

OK here the answer for your question,

Ex:1% of 2 = 1/100*2 = 1/50.

10% of 100 = 10/100*100 = 10.

So now come to our problem ok.

Take speed of the car is X ok. (Consider 100).

Train is 50% faster ok so 100+50 = 150;.

So we need find that 150%X which gives 150/100*X.

All the best.

Still I have a one confusion in my mind that why we are taking speed of a train as,

(50% of car+x) instead of 50% more i.e (50%+x).

We need to convert 12.5 min to hours because the options given are in kmph (kilometre per hour).

To convert 12.5 min to hours you divide it by 60.

To make calculation easier 12.5 is converted into 125 by multiplying it by 10. If you multiply numerator with a number, then you also have to multiply denominator by that number.

Hence in this case it will be 12.5*10/60*10 = 125/600 which is actually the same as 12.5/60.

125/600 = 5/24.

12.5/60 = 5/24.

How 125/ (10*60) came?. Anyone please explain this point.

Can you please tell me how that 125/(10x60) came?

Here 150/100 how it come means.

Actually they said train 50%more than speed of car.

So train actually speed was 100% means 100/100 and he said 50 more so 150/100 that's it.