Aptitude - Time and Distance - Discussion

Distance=600km
Speed=200km
Time=x+30mins

So we have to the time duration,
Time = Distance/speed.
x+30=600/200,
x+30=3,
x=3-30,
x=27mins(neglect the negative),
x=27+30min,
x=57 mins(Almost 1hr),

Ans x=1hr.

@Patreppa.

((2x+1)600-1200x)/x(2x+1)=200
(1200x+600-1200X)=200*x(2x+1)
600=200(2x^2+x)
600=400x^2+200x
400x^2+200x-600=0

Divide by 200 then(just for simplification).

2x^2 + x - 3 = 0.

Yesh, I understood till,

(600/x) - (1200/(2x+1)) = 200.

Please, can anybody simplify this, only let me know, please.

Another simple way of doing this is solve by;

600/(x-200)- 600/(x) = 1/2.
we get x= 600km/hr.

Time=distance/speed = 600/600 = 1hr.

In question avg speed given:

The avg speed= total distance/total time elapsed
So according to question the equation becomes:
1200/2t - 200 =1200/(2t+1/2).

After solving,
4t^2+t-3=0,
(4t+3)(t-1)=0,
so t=1;(taking positive value).

Suppose,
Duration = x hour.
600-200 = 400,
ATq,
x/400 - x/600 = 1/2,
2x = 1200,
x = 600,
So,
duration = 600/600 = 1 hour.

I solve this problem like this

First, I check the facts given:
Distance = 600km.
Original speed = we don't know,
New speed = we don't know,
The Relation between new and original speed = new speed is 200km/h slower to original speed so the diff in speed is 200km/h.
Original time = we don't know,
New time = we don't know,
Relation between new and original Time = new time is 30minutes more than original time so the diff in time is an hour.

Now, I need two separate numbers with the diff of 200 and should be able to divide 600 with a diff of .5 (means) and the numbers are 600 and 400.

600/600 = 1 (original speed 600km/h and it takes 1 hour to reach).
600/400 = 1.5 (new speed 400km/h and it takes 1 hour 30 min to reach).

Thanks for your valuable explanation @Bhavana.

Hi, in question they mentioned.

d=600km , s=200kmph , t=30min.

Let duration of flight = x.

wkt SPEED=DISTANCE/TIME (s=d/t).
200 = 600/x - 600/x+(30/60).
200 = 600/x - 600*2/2x+1.

By solving this we get,
2x^2+2x-x = 0,
x=1.

Hi, Can anyone tel that how to calculate speed and what is the final answer?