15
Q:

A son and father goes for boating in river upstream . After rowing for 1 mile son notices the hat of his father falling in the river. After 5 min he tells his father that his hat has fallen. So they turn round and are able to pick the hat at the point from where they began boating after 5min. Find the speed of river  in miles/hours ?

A) 4 mile/hr B) 6 mile/hr
C) 2 mile/hr D) 5 mile/hr

Answer:   B) 6 mile/hr



Explanation:

Let the speed of river and boat be 'r' m/min and 'b' m/min.
so relative speed in upstream (b-r)m/min and in downstream (b+r)m/min.
Now in upstream distnce covered in 5 min is 5(b-r)miles
so total distnce covered => 1 + 5(b-r)miles in upstream
In downstream distance covered in 5min is 5(b+r)miles
Now 1 + 5(b-r) = 5(b+r)
1+5b-5r = 5b+5r
1 = 10r
r = 1/10 mile/min => 6 mile/hr.

Q:

Which of the following pairs are co-primes?

 

 

A) 59, 97 B) 348, 296
C) 3025, 4920 D) 114, 213
 
Answer & Explanation Answer: A) 59, 97

Explanation:
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0 118
Q:

A man travels from point A to B at 40 km/hr and returns from B to A at 60 km/hr. What is his average speed during the whole journey?

 

A) 55 km/hr B) 45 km/hr
C) 48 km/hr D) 50 km/hr
 
Answer & Explanation Answer: C) 48 km/hr

Explanation:
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0 120
Q:

The distance between two stations A and B is 575 km. A train starts from station ‘A’ at 3:00 p.m. and moves towards station ‘B’ at an average speed of 50 km/h. Another train starts from station ‘B’ at 3:30 p.m. and moves towards station ‘A’ at an average speed of 60 km/h. How far from station ‘A’ will the trains meet ?

 

 

A) 275 km B) 325 km
C) 300 km D) 225 km
 
Answer & Explanation Answer: A) 275 km

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0 162
Q:

A car covers a distance of 20 km in 15 minutes. If its speed is decreased by 10 km/hr, then what will be the time (in minutes) taken by it to cover the same distance?

 

A) 150/11 B) 120/7
C) 130/11 D) 150/13
 
Answer & Explanation Answer: B) 120/7

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2 150
Q:

A boy walking at the speed of 3 km/hr covers a certain distance in 3 hours 40 minutes. If he covers the same distance by cycle in 11 hours, then what is the speed (in km/hr) of cycle?

 

A) 1 B) 2
C) 4 D) 3
 
Answer & Explanation Answer: A) 1

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0 137
Q:

A aid can cycle at 16 km/h and walk at 7 km/h. To cover a distance of 109 km. she takes 8.5 hours. How much distance did she cover on foot?

 

A) 17.5 km B) 24.5 km
C) 21 km D) 28 km
 
Answer & Explanation Answer: C) 21 km

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0 306
Q:

Mark had to travel 220 km in 4.5 hours, using a train that travels at the speed of 60 km/h or a bus that travels at the speed of 40 km/h, or any combination of the two modes of transport. For how long did he travel by bus?

 

A) 1 hour B) 1 hour 30 minutes
C) 2 hours 30 minutes D) 2 hours
 
Answer & Explanation Answer: C) 2 hours 30 minutes

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0 158
Q:

Rain swims in an 80 in long pool. He covers 160 m in one minute by swimming from one end to the other and back, along the same straight path. Find his average speed.

 

A) 2.07 ms-1 B) 2.60 ms-1
C) 3.67 ms-1 D) 2.67 ms-1
 
Answer & Explanation Answer: D) 2.67 ms-1

Explanation:
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0 167