Aptitude - Time and Distance - Discussion
Discussion Forum : Time and Distance - General Questions (Q.No. 12)
12.
Robert is travelling on his cycle and has calculated to reach point A at 2 P.M. if he travels at 10 kmph, he will reach there at 12 noon if he travels at 15 kmph. At what speed must he travel to reach A at 1 P.M.?
Answer: Option
Explanation:
Let the distance travelled by x km.
| Then, | x | - | x | = 2 |
| 10 | 15 |
3x - 2x = 60
x = 60 km.
| Time taken to travel 60 km at 10 km/hr = |  |
60 |  hrs |
= 6 hrs. |
| 10 |
So, Robert started 6 hours before 2 P.M. i.e., at 8 A.M.
 Required speed = |
|
60 | kmph. |
= 12 kmph. |
| 5 |
Discussion:
93 comments Page 3 of 10.
Erigela vani said:
6 years ago
@Shivasai.
I think here the difference between the two times I. E12noon and 2pm is 2, and also time =d÷s, so we should take distance as "X" and speeds which they are given so x÷10-x÷15=2.
I think here the difference between the two times I. E12noon and 2pm is 2, and also time =d÷s, so we should take distance as "X" and speeds which they are given so x÷10-x÷15=2.
Noorandeous said:
6 years ago
6 hours before 2 PM was not given how you added it?
Ram sai said:
6 years ago
Thanks for the answer @Ashish.
Muhammad ali said:
6 years ago
Why don't you just find the mean value?
With 10kmph reach at 2 p.m.
Witn 15kmph reach at 12noon.
Find mean of both for 1p.m required time.
So, 10+15 = 25/2 = 12.5kmph should be the correct answer.
With 10kmph reach at 2 p.m.
Witn 15kmph reach at 12noon.
Find mean of both for 1p.m required time.
So, 10+15 = 25/2 = 12.5kmph should be the correct answer.
(1)
Abhi said:
6 years ago
How 60/5 comes, does any one please tell me?
Shivasai said:
6 years ago
Then, x/10 - x/15 = 2 why we have taken this?
What is the logic behind it
What is the logic behind it
Pavan sai said:
7 years ago
It's very easy by using relative speed concept there are two things up there.
So, now by using the formula 2xy/x+y.
where x=10 and y=15,
=> 2*10*15/10+15,
=>300/25,
=>12,
So the answer is 12kmph.
So, now by using the formula 2xy/x+y.
where x=10 and y=15,
=> 2*10*15/10+15,
=>300/25,
=>12,
So the answer is 12kmph.
(2)
Subash said:
7 years ago
Thanks for the answer @Raja.
Bhushan suriya said:
7 years ago
Consider starting time as x.
We know that time = (distance/speed),
When he reach at 2 P.M i.e.,14.00 (railway time)
(14-x) = (distance/ 10)
When he reach at 12 P.M
(12-x) = (distance/15)
As we know that., distance is the same.
So, from above equations we get x=8. so he started cycling at 8 A.M.
So from this, we can calculate distance = 60 km.
To reach at 1 P.M, the time taken is 5 hrs.
Speed = (60/5) = 12 kmph.
We know that time = (distance/speed),
When he reach at 2 P.M i.e.,14.00 (railway time)
(14-x) = (distance/ 10)
When he reach at 12 P.M
(12-x) = (distance/15)
As we know that., distance is the same.
So, from above equations we get x=8. so he started cycling at 8 A.M.
So from this, we can calculate distance = 60 km.
To reach at 1 P.M, the time taken is 5 hrs.
Speed = (60/5) = 12 kmph.
Raman Sharma said:
7 years ago
Distance = speed * time.
For time ,let say time taken to travel to point A = t.
d = 15*t ------- eqn.1
d = 10(t+2) ------eqn. 2
d = s* (t+1)--------- eqn. 3.
From eqn 1 and eqn 2
15* t = 10(t+2).
after solving, t = 4 means time to travel is 4 hours.
now,
we put value of t = 4 in eqn 3 and eqn. 2.
60 = s(4+1).
s = 12 kmph.
For time ,let say time taken to travel to point A = t.
d = 15*t ------- eqn.1
d = 10(t+2) ------eqn. 2
d = s* (t+1)--------- eqn. 3.
From eqn 1 and eqn 2
15* t = 10(t+2).
after solving, t = 4 means time to travel is 4 hours.
now,
we put value of t = 4 in eqn 3 and eqn. 2.
60 = s(4+1).
s = 12 kmph.
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