Mathematics Mcqs

A boy goes to his school from his house at a speed of 3 km / hr and returns at a speed of 2 km / hr. If he takes 5 hours in going and coming, the distance between his house and school is :___________?

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A boy goes to his school from his house at a speed of 3 km / hr and returns at a speed of 2 km / hr. If he takes 5 hours in going and coming, the distance between his house and school is :___________?

A. 5 km
B. 5.5 km
C. 6 km
D. 6.5 km
Average speed = ( 2 X 3 X 2/3 + 2 ) km/ hr = 12/5 km/ hr. Distance travelled = ( 12/5 X 5 )km = 12 km. So Distance between house and school = ( 12/2 )km = 6 km.

An express train travelled at an average speed of 100 km / hr, stopping for 3 minutes after every 75 km. How long did it take to reach its destination 600 km from the starting point ?

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An express train travelled at an average speed of 100 km / hr, stopg for 3 minutes after every 75 km. How long did it take to reach its destination 600 km from the starting point ?

A. 6 hrs 21 min
B. 6 hrs 24 min
C. 6 hrs 27 min
D. 6 hrs 30 min
Time taken to cover 600 km = ( 600/100 ) hrs = 6 hrs. Number of stoppages = ( 600/75 – 1 ) = 7 Total time of stoppage = (3 x 7) min = 21 min. Hence, total time taken = 6 hrs 21 min.

A walks around a circular field at the rate of one round per hour while B runs around it at the rate of six rounds per hour. They start in the same direction from the same point at 7.30 a.m. They shall first cross each other at :___________?

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A walks around a circular field at the rate of one round per hour while B runs around it at the rate of six rounds per hour. They start in the same direction from the same point at 7.30 a.m. They shall first cross each other at :___________?

A. 7.42 a.m.
B. 7.48 a.m.
C. 8.10 a.m.
D. 8.30 a.m.

A train covers a distance of 10 km in 12 minutes. If its speed is decreased by 5 km /hr, the time taken by it to cover the same distance will be :__________?

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A train covers a distance of 10 km in 12 minutes. If its speed is decreased by 5 km /hr, the time taken by it to cover the same distance will be :__________?

A. 10 min
B. 11 min 20 sec
C. 13 min
D. 13 min 20 sec
Speed = (10 X 60/12 ) km/hr = 50 km/hr. New speed = (50 – 5) km / hr = 45 km /hr. So Time taken = ( 10/45 ) hr = ( 2/9X 60 )min 131/3 min = 13 min 20 sec.

A boat having a length 3 m and breadth 2 m is floating on a lake The boat sinks by 1 cm when a man gets on it. The mass of man is :__________?

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A boat having a length 3 m and breadth 2 m is floating on a lake The boat sinks by 1 cm when a man gets on it. The mass of man is :__________?

A. 12 kg
B. 60 kg
C. 72 kg
D. 96 kg
Volume of water displaced = (3 X 2 X 0.01) m3 = 0.06 m3.
Mass of man = Volume of water displaced X Density of water
= (0.06 X 1000) kg = 60 kg.

The areas of the three adjacent faces of a rectangular box which meet in a point are known. The product of these areas is equal to :___________?

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The areas of the three adjacent faces of a rectangular box which meet in a point are known. The product of these areas is equal to :___________?

A. the volume of the box
B. twice the volume of the box
C. the square of the volume of the box
D. the cube root of the volume of the box
Let length = 1, breadth = b and height = h. Then,
Product of areas of 3 adjacent faces = (lb x bh x 1h) = (lbh)2 = (Volume)2.