Latest Questions, General Mathematics

Question: The ratio between the rates of walking of A and B is 2 : 3. If the time taken by B to cover that much distance is :
A
24

B
38

C
48

D
54

Note: Ratio of rates of working = inverse ratio of time taken `:. 2/3 = 36/x => 2x = 108 => x = 54` min.
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Question: I have to be at a certain place at a certain time and find that I shall be 20 minutes too late if I walk at 3 km/hr and 10 minutes too soon if I walk at 4 km/hr. How far I have to walk ?
A
6 km

B
10 km

C
`12 1/2` km

D
`16 2/3` km

Note: Let the distance be x km `x/3 - x/4 = 30/60 => x/12` `= 1/2 => x = 6 km`
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Question: Sound travels at 330 metres a second.How many kilometres away is a thunder cloud when its sound follows the flash after 10 seconds ?
A
3.3

B
33

C
0.33

D
3.33

Note: Distance `= (time xx speed)` `= (330 xx 10) m` `= (330 xx 10)/(1000) km` = 3.3
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Question: Walking `6/7 th of his usual speed, a man is 12 minutes too late. The usual time taken by him to cover that distance is :
A
1 hour

B
1 hour 12 min

C
1 hour 15 min

D
1 hour 20 min

Note: New speed` = 6/7` of the usual speed. New time taken` = 7/6` of the usual time `(7/6 of usual time)` - (usual time) = 12 min. `:. 1/6` of usual time = 12 min. or usual time = 72 min.
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Question: A is twice as fast as B and B is thrice as fast as C. The journey covered by C in 42 minutes will be covered by A in :
A
7 min.

B
14 min.

C
28 min.

D
35 min.

Note: Not available
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Question: A car takes 5 hours to cover a distance of 300 km. How much should the speed in km/hr be maintained to cover the same distance in`4/5` th of the previous time ?
A
48

B
60

C
75

D
120

Note: Distance = 300 km. Time required` = (4/5 xx 5) = 4` hours Speed` = (300/4) = 75` km/hr
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Question: Two men start together to walk a certain distance at 3.75 km and 3 km per hour respectively. The former arrives 30 minutes before the later. The distance they walked is :
A
7.5 km

B
10 km

C
12.5 km

D
15 km

Note: Suppose they walked x km.Then, `x/3 - x/(3.75)` `= 30/60 => (0.75 x)/(3 xx 3.75)` `= 1/2` `:. x = (3 xx 3.75)/(1.5)` `= 7.5 km`
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Question: The wheel of a an engine`7 1/2` metres in circumference makes 7 revolutions in 9 seconds. The speed of the train in km per hour is :
A
150

B
132

C
130

D
135

Note: Distance covered in 7 revolutions `= (7 xx 2 xx 22/7 xx 15/2) m` `= 330 m.` Distance covered in 9 sec m. Distance covered in 1 hour `= (330/9 xx (60 xx 60)/(1000)) m` `= 132 km`
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Question: A train X starts from the same place at the speed of 50 km/hr.After how much time will Y cross X ?
A
3 hrs

B
`2 3/4 hrs`

C
`3 1/2 hrs`

D
`2 1/4 hrs`

Note: Suppose they cross after x hours. Distance covered by Y in (x - 1) hours = Distance covered by X in x hours 70 (x - 1) = 50 x => x = 3 1/2`
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Question: A person travels equal distance with speeds of 3 km/hr, 4 km/hr and 5 km/hr and takes a total time of 47 minutes. The total distance (in km) is :
A
2

B
3

C
4

D
5

Note: `x/3 + x/4 + x/5` `= 47/60 => 20x + 15x + 12x` `= 47 => x = 1` :. Total distance` = (1 + 1 + 1) km` `= 3 km`
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Question: The ratio between the rates of walking of A and B is 2 : 3. If the time taken by B to cover that much distance is :

Question: I have to be at a certain place at a certain time and find that I shall be 20 minutes too late if I walk at 3 km/hr and 10 minutes too soon if I walk at 4 km/hr. How far I have to walk ?

Question: Sound travels at 330 metres a second.How many kilometres away is a thunder cloud when its sound follows the flash after 10 seconds ?

Question: Walking `6/7 th of his usual speed, a man is 12 minutes too late. The usual time taken by him to cover that distance is :

Question: A is twice as fast as B and B is thrice as fast as C. The journey covered by C in 42 minutes will be covered by A in :

Question: A car takes 5 hours to cover a distance of 300 km. How much should the speed in km/hr be maintained to cover the same distance in`4/5` th of the previous time ?

Question: Two men start together to walk a certain distance at 3.75 km and 3 km per hour respectively. The former arrives 30 minutes before the later. The distance they walked is :

Question: The wheel of a an engine`7 1/2` metres in circumference makes 7 revolutions in 9 seconds. The speed of the train in km per hour is :

Question: A train X starts from the same place at the speed of 50 km/hr.After how much time will Y cross X ?

Question: A person travels equal distance with speeds of 3 km/hr, 4 km/hr and 5 km/hr and takes a total time of 47 minutes. The total distance (in km) is :