Aptitude - Time and Distance - Discussion

Simply,

(2/1000) = 0.002km/sec
Then (0.002*3600) = 7.2km/sec.

Note: small quantity to big quantity then divide i.e; 2/1000 = meter into kms.

@Snehql.

It took 15 hrs.

Can anyone please help me for solving this question?

A boat goes 8 km downstream in 40 min and returns to the same point in 1 hr how much time will it take to cover a distance of 144 km in still water?

= D/t
= 600/5 * 60 * 18/5,
= 7.2.

Thanks, @Priya.

Your explanation simple and good.

Speed = dis/time so speed = 600/5 convert it directly to km/hr (1 km= 1000m and1 hour = 60 minutes).

So, speed = 600*60/5*1000 = 7.2km/hr.

Easy way to solve this problem.

Speed=Distance/Time.
Now,
1km=1000m,
1/1000km=1m,
600/1000km=600m,
i.e. 0.6km=600m,
1hr=60min,
1/60hr=1min,
5/60hr=5min, i.e. 0.083hr=5min.

speed=distance/time.
=(600/5)m/sec.
=(0.6/0.083)km/hr.
speed=7.22km/hr.

@Dorothyeva.

Speed = distance /time.
D=600 m,
T=5 minutes,
T=5*60 sec,
Now put into formula.

Speed= 600/300 (m/s).
But we are required to find it in km/hr.
Km/hr......> m/s. (Multiply it by 5/18).
m/s..........> km/hr. (Multiply it by 18/5).
S =(600/300) * 18/5.
S=36/5.
Speed = 7.2 km/hr.

The speed formula= distance/time.

So we have speed=600 metres/ 5 min
In this 5 is a minute value so we have to convert it into seconds
Because metres/seconds is a current formula
so we need to change the 5 min value into seconds
1 min= 60 seconds.
So 5 min = 5*60.
= 300 sec that's why 60 will come in this section
now we calculate speed = 600/300 m/sec.
= 2 m/sec

On step 2:
we need the man speed in km/hour.
so we need to convert m/sec into km/hour.
using 1000/3600= 5/18.
Because 1 km= 1000 m.
and 1 hour= 3600 sec ( 1min= 60 sec then 1hour= 60 min so 60*60= 3600 sec)
the answer is 2*5/18= 7.2 km/hour.

I do not understand where 18 came from? Please Explain me.