The distance between two cities A and B is 330 km. A train starts from A at 8 a.m. and travels towards B at 60 km/hr. Another train starts from B at 9 a.m. and travels towards A at 75 km/hr. At what time do they meet?
(a) 10:30 am
(b) 10:45 am
(c) 11 am
(d) 11:25 am
(e) None of these
Answer: (c)
Suppose they meet x hrs after 8 a.m.
Then, (Distance moved by first in x hrs) + [Distance moved by second in (x – 1)hrs] = 330
60x + 75(x – 1) = 330
x = 3
So, they meet at (8 + 3), i.e. 11 a.m
A man rows 750m in 775 seconds against the stream and returns in \(\displaystyle 7\frac{1}{2}\) minutes. What is rowing speed in still water?
(a) 4.7 km/hr
(b) 4 km/hr
(c) 3.5 km/hr
(d) 6 km/hr
(e) None of these
Answer: (a)
Speed upstream ‘b’ = 750m / 775 sec = 30/31 m/sec
Speed downstream ‘a’ = 750 m/ (15/2) minutes [1 min=60 sec] a = 750m/450 sec = 5/3 m/sec speed in still water
A train travels at a speed of 40 km/h and another train at a speed of 20 m/s. What is the ratio of speed of the first train to that of the second train?
(a) 2 : 1
(b) 5 : 9
(c) 5 : 3
(d) 9 : 5
(e) None of these
Answer: (b)
Speed of a train = 40 km/h
\(\displaystyle 40\times \frac{5}{{18}}m/s\)
Speed of another train = 20 m/s
Required ratio = \(\displaystyle \frac{{speedoffirsttrain}}{{speedof\sec ondtrain}}\)
Two trains of length 110 m and 90 m are running on parallel lines in the same direction with a speed of 45km/h and 50 km/h respectively. In what time will they pass other?
