Question

Two people a and b are at a distance of 110 km from each other at 10:30 am. After 30 mins, a starts moving towards b at a speed of 20 km/hr while at 12 pm. B starts moving away from a at a speed of 15 km/hr. At what time (in am) will they meet on the next day

Answer 1

Let the distance between Meerut and Ghaziabad be
d
km

First train covers distance
d
km in 1 hr

Speed of the first train
=
d
1
=
d
km/hr


Second train covers distance
d
km in
1
1
2
=
3
2
hr

Speed of the second train
=
d
(
3
2
)
=
2
d
3
km/hr

Let the trains meet
x
hours after 4 pm

Distance travelled by first train in
x
hours
=
x
×
d
km
Distance travelled by second train in
x
hours
=
x
×
2
d
3
km

Sum of these distances must be the total distance between Meerut and Ghaziabad
x
×
d
+
x
×
2
d
3
=
d
x
+
2
x
3
=
1
5
x
3
=
1
x
=
3
5
hr
=
36
min


i.e., the trains will cross each other at 4:36 pm
bro we can take two as a train