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Q:

In a college, the ratio of the number of boys to girls is 8 : 5. If there are 160 girls, the total number of students in the college is

A) 100 B) 250
C) 260 D) 416
 
Answer & Explanation Answer: D) 416

Explanation:

Let the number of boys and girls be 8x and 5x.
Total number of students = 13x = 13 * 32 = 416.

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Filed Under: Ratios and Proportions

Q:

The salaries of A, B, and C are in the ratio of 1 : 2 : 3. The salary of B and C together is Rs. 6000. By what percent is the salary of C more than that of A?

A) 100 % B) 200%
C) 300% D) 600%
 
Answer & Explanation Answer: B) 200%

Explanation:

Let the salaries of A, B, C be x, 2x and 3x respectively.

Then,2x + 3x = 6000  => x = 1200.

A's salary = Rs. 1200, B's salary = Rs. 2400, and Cs salary Rs. 3600.
Excess of C's salary over A's=[ (2400 /1200) x 100] = 200%.

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Filed Under: Ratios and Proportions

Q:

A mixture contains alcohol and water in the ratio 4:3. If 5 liters of water is added to the mixture, the ratio becomes 4:5. Find the quantity of alcohol in the given mixture.

A) 8 Liters B) 10 Liters
C) 18 Liters D) 22 Liters
 
Answer & Explanation Answer: B) 10 Liters

Explanation:

Let the quantity of alcohol and water be 4x liters and 3x liters respectively. Then,

 

(4x)/(3x+5) = 4/5

 

=> 20x = 4(3x+5) 

 

=> x = 2.5 

 

Quantity of alcohol = (4 * 2.5) liters = 10 liters.

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Filed Under: Ratios and Proportions

Q:

There is certain numbers of toys in the box. They are divided into such a way that the person who gets 1/4 of the whole gets thrice of what the others get on an average. Find the number of people amongst whom the toys are distributed?

A) 8 B) 10
C) 12 D) 9
 
Answer & Explanation Answer: B) 10

Explanation:

If the person who gets 1/4 of the whole gets thrice of what the others get on an average, each one will get =1/3×1/4=112 of the whole.
Therefore, if there are k persons other than the person who gets one-fourth, then 1/4 + k/12 = 1
⇒ k=9

Hence, total number of people = 10.

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Filed Under: Ratios and Proportions

Q:

Two cogged wheels of which one has 32 cogs and other 54 cogs, work into each other. If the latter turns 80 times in three quarters of a minute, how often does the other turn in 8 seconds?

A) 48 B) 24
C) 38 D) 36
 
Answer & Explanation Answer: B) 24

Explanation:

Less Cogs  more turns and less time  less turns

 

    Cogs  Time  TurnsA  54       45       80B   32       8          ?

Number of turns required=80 × 54/32 × 8/45  = 24 times

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Filed Under: Problems on Trains

Q:

A train 800 metres long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 minute, then the length of the tunnel (in meters) is :

A) 130 B) 360
C) 500 D) 540
 
Answer & Explanation Answer: C) 500

Explanation:

Speed =[ 78 x ( 5/18 ) ] m/sec = 65/3 m/sec.

 

Time = 1 minute = 60 sec.

 

Let the length of the tunnel be x metres.

 

Then, [ (800 + x )/ 60 ]= 65/3

 

3(800 + x) = 3900

 

 x = 500.

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Filed Under: Problems on Trains

Q:

A train travelling at a speed of 75 mph enters a tunnel 312miles long. The train is 14mile long. How long does it take for the train to pass through the tunnel from the moment the front enters to the moment the rear emerges?

A) 2.5 min B) 3 min
C) 3.2 min D) 3.5 min
 
Answer & Explanation Answer: B) 3 min

Explanation:

Total distance covered =72+14miles =154miles  

Time taken = 154*75hrs = 120 hrs =120*60min = 3 min

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Filed Under: Problems on Trains

Q:

A train 110 metres long is running with a speed of 60 kmph. In what time will it pass a man who is running at 6 kmph in the direction opposite to that in which the train is going?

A) 5 B) 6
C) 7 D) 10
 
Answer & Explanation Answer: B) 6

Explanation:

Speed of train relative to man = (60 + 6) km/hr = 66 km/hr.

[66*(5/18)] m/sec = (55/3) m/sec

Time taken to pass the man = [110*(3/55)]m/sec = 6 sec.

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Filed Under: Problems on Trains