Two trains of 200 m and 100 m long are running parallel at the rate of 20 m/sec. and 22 m/sec. respectively. How much time will they take to cross each other, if the trains are running along the same direction? [#1132]
Q1. Two trains of 200 m and 100 m long are running parallel at the rate of 20 m/sec. and 22 m/sec. respectively. How much time will they take to cross each other, if the trains are running along the same direction? Q1. Two trains of 200 m and 100 m long are running parallel at the rate of 20 m/sec. and 22 m/sec. respectively. How much time will they take to cross each other, if the trains are running along the same direction?
(A) 120 sec (A) 120 sec
(B) 100 sec (B) 100 sec
(C) 60 sec (C) 60 sec
(D) 50 sec (D) 50 sec
Answer: (D) 50 sec Answer: (D) 50 sec
The difference of speed = 22m/s - 20m/s = 2m/s
As the train with speed 22m/s will cross the other, hence this train have to go the smallest length of the trains distance ahead of the other to cross completely.
Hence This train will be ahead of 100m with a speed of 2m/s.
Hence The time to cross each other will take = 100m / (2m/s)
= 50 secThe difference of speed = 22m/s - 20m/s = 2m/s
As the train with speed 22m/s will cross the other, hence this train have to go the smallest length of the trains distance ahead of the other to cross completely.
Hence This train will be ahead of 100m with a speed of 2m/s.
Hence The time to cross each other will take = 100m / (2m/s)
= 50 sec
Q2. At what speed should a car travel on a highway to reach a destination 12 km away in 15 minutes? Q2. At what speed should a car travel on a highway to reach a destination 12 km away in 15 minutes?
(A) 64 kmph (A) 64 kmph
(B) 84 kmph (B) 84 kmph
(C) 48 kmph (C) 48 kmph
(D) 36 kmph (D) 36 kmph
Answer: (C) 48 kmph Answer: (C) 48 kmph
12
---- x 60 = 48 KMPH
1512
---- x 60 = 48 KMPH
15
Q3. The sum of the four consecutive alternate numbers is 64. The smallest number amongst them is Q3. The sum of the four consecutive alternate numbers is 64. The smallest number amongst them is
(A) 13 (A) 13
(B) 11 (B) 11
(C) 16 (C) 16
(D) 9 (D) 9
Answer: (A) 13 Answer: (A) 13
The smallest number amongst them is 13
=> X + (X+2) + (X+4) + (X+6) = 64
=> 4X + 12 = 64
=> 4X = 64 - 12
=> 4X = 52
=> X = 13The smallest number amongst them is 13
=> X + (X+2) + (X+4) + (X+6) = 64
=> 4X + 12 = 64
=> 4X = 64 - 12
=> 4X = 52
=> X = 13
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