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Q:

There are 100 students in 3 sections A, B and C of a class. The average marks of all the three sections was 84. The average of B and C was 87.5 and the average marks of students in A section was :

A) 20 B) 35
C) 54 D) 40
 
Answer & Explanation Answer: A) 20

Explanation:

Numbers of students in section A = x
∴ Numbers of students in section B and C = (100 – x)
∴ x 70 + (100 – x) 87.5 = 84 100
=> 70x + 87.5 100 – 87.5x = 8400
=> 8750 – 17.5x = 8400
=> 17.5x = 8750 – 8400 => x = 20.

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Filed Under: Average
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Q:

The circumferences of two circles are 264 meters and 352 meters. Find the difference between the areas of the larger and the smaller circles  ?

A) 2413 sq.m B) 1234 sq.m
C) 4312 sq.m D) 2143 sq.m
 
Answer & Explanation Answer: C) 4312 sq.m

Explanation:

Let the radii of the smaller and the larger circles be 's' m and 'l' m respectively.  

 2πs = 264 and 2πl = 352  

 

 s = 2642π and l = 3522π   

Difference between the areas =πl2-πs2   

  = π1762π2-1322π2 

  = 1762π-1322π  

  = (176 - 132)(176 + 132) / π  

  = (44 x 308) / (22/7) = 4312 sq.m

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Filed Under: Volume and Surface Area
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Q:

10 boys can complete a work in 7 days and 10 girls take 14 days to complete the work. How many days will 5 boys and 10 girls take to complete the work ?

A) 13 days B) 10 days
C) 7 days D) 16 days
 
Answer & Explanation Answer: C) 7 days

Explanation:

1 boy's 1 day work = 1/70

1 girl's 1 day work = 1/140

(5 boys + 10 girls)'s 1 day work = (5/70 + 10/140) = (1/14 + 1/14) = 1/7

 

5 boys and 10 girls will complete the work in 7 days.

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Filed Under: Time and Work
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Q:

Vishal and Raghu jointly started a business. Vishal invested three times as Raghu did and invested his money for double time as compared to Raghu. Raghu earned Rs. 4000. If the gain is proportional to the money invested and the time for which the money is invested then the total gain was  ?

A) Rs. 28,000 B) Rs. 18,000
C) Rs. 14,000 D) Rs. 8,000
 
Answer & Explanation Answer: A) Rs. 28,000

Explanation:

Investments ratio is = 3:1
Time period ratio is = 2:1

As they are proportional to gain

------
Gain ratio of Vishal and raghu = 6:1

But given Raghu got Rs. 4000, 

=? 1 ----- 4000
     7 -----    ?

=> Rs.28,000

The total gain = Rs.28,000

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Filed Under: Partnership
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Q:

When 0.46 is written in simplest form, the sum of the numerator and the denominator is  ?

A) 69 B) 73
C) 96 D) 41
 
Answer & Explanation Answer: B) 73

Explanation:

0.46 = 46/100 = 23/50.

Sum of the numerator and denominator is 23 + 50 = 73

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Filed Under: Decimal Fractions
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Q:

P is faster than Q. P and Q each walk 24 km. The sum of their speeds is 7 km/hr and the sum of times taken by them is 14 hours. Then, P's speed is equal to ?

A) 3 km/hr B) 4 km/hr
C) 5 km/hr D) 6 km/hr
 
Answer & Explanation Answer: B) 4 km/hr

Explanation:

Let P's speed = x km/hr. Then, Q's speed = (7 - x) km/ hr.

 

So, 24/x + 24/(7 - x) = 14

 

x2 - 98x + 168 = 0

 

(x - 3)(x - 4) = 0 => x = 3 or 4.

 

Since, P is faster than Q,

 

so P's speed = 4 km/hr and Q's speed = 3 km/hr.

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Filed Under: Time and Distance
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Q:

Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively and they cross each other in 23 seconds. The ratio of their speeds is  ?

A) 1 : 2 B) 3 : 1
C) 4 : 7 D) 3 : 2
 
Answer & Explanation Answer: D) 3 : 2

Explanation:

Let the speeds of the two trains be x m/sec and y m/sec respectively.

Then, length of the first train = 27 x meters, and

length of the second train = 17 y meters.

(27 x + 17 y) / (x + y) = 23

=> 27 x + 17 y = 23 x + 23 y

=> 4 x = 6 y

=> x/y = 3/2.

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Q:

A laborer is engaged for 30 days on the condition that he receives Rs.25 for each day he works and is fined Rs.7.50 for each day is absent. He gets Rs.425 in all. For how many days was he absent ?

A) 10 days B) 14 days
C) 11 days D) 9 days
 
Answer & Explanation Answer: A) 10 days

Explanation:

For 30 days he receives

30 x 25 = 750
               

Actually he gets 425

Therefore, Fine is 750 - 425 =  325

 

=> No of days absent = 325/(25+7.50)= 10

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Filed Under: Time and Work
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