Goforexam.in Guide for Placements, Interview, Aptitude Test...

Below are three problems dealing with speed and time calculations. Question 1 Two buses leaving from two stations 20 km away from each other travel with constant speed of 45km/hr towards each other.Find the time taken to cross each other if the length of each bus is 100m. a)10sec b)4sec c)15sec d)20sec Answer : b)4sec Solution : The time taken to cross each other = (a + b) / (u + v) sec. Here, a = b = length of the two buses = 100m = 1/10 km. and u = v = speed of the two buses = 45km/hr. Time taken to cross each other = (a + b) / (u + v) sec = (1/10 + 1/10) / (45 + 45) hours 1 / (10 x 90) = 1/900 hours. since 1 hour = 3600 sec, 1/900 hour = 3600/900 = 4 sec Hence the answer is 4 sec. Question 2 A bus starts from A at 7 a.m and reaches the destination B at 7.30 a.m while a cyclist starts from B at 7 a.m and reaches A at 8.30 a.m. At what time the bus and the cyclist will cross each other? a)7.34 a.m b)7.49 a.m c)7.23 a.m d)8.01 a.m Answer : c)7.23a.m Soluti...

Question 1 A policeman starts chasing a thief 30 minutes after the thief had run from a spot. With an average speed of 20km per hour, he takes 2 hours to catch the thief. What is the average speed of the thief? a)16km/hr b)25km/hr c)24km/hr d)18km/hr Answer : a)16km/hr Solution: As given, the average speed of the policeman = 20km/hr. He takes 2 hours to catch the thief, so from formula, "distance = speed x time" we have The total distance covered by the police to catch the thief = 20 x 2 = 40 km (This value is also equal to the distance run by thief before being caught by Police.) Policeman had started late by 30 minutes and took 2 hours to catch the running thief. Above means that the thief takes (30minutes + 2 hours =) 5/2 hours to reach 40km. So the speed of the thief = 40/(5/2) = 40 x 2 / 5 = 16 km/hr. Hence the answer is 16km/hr. Question 2 From a particular spot, Tom started to chase Jerry which had left the spot before 30 minutes. Tom ran acro...

1. Speed of boat in still water is 10kmph..if it travels 24km downstream,16km upstream in the same amount of time,what is the speed of the stream? (a)3kmph (b)3.5kmph (c)2kmph (d)... 2. A cube of 3 units is painted on all sides. If this cube is divided into cubes of 1 unit,how many cube have none of their faces painted? (a)... (b)2 (c)1 (d)0 (e)none of these 3. If a person sells a product for rs141/- he suffers a loss of 6%.if he has to have a profit of 10%, at what price should he sell it? (a) (b)rs.175 (c).. (d)rs.165 ans. rs.165 (i think,check) 4. A ball falls from a height of 8ft ,bounces back to half the distance & continues till it comes to rest. what is the total distance travelled by the ball? (a)24ft (b)... (c)infinite (d)cannot be determined ans:(a) 5. Which of the following is the sum of 3 consecutive prime nos? (a)49 (b)59 (c)both a &b (d).... ans:c 6. If the area of a square has increased by 69%,by what % has its side increased? 7. In a class the average age is 16...