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Q:

In a class of 60 students, the number of boys and girls participating in the annual sports is in the ratio 3 : 2 respectively. The number of girls not participating in the sports is 5 more than the number of boys not participating in the sports. If the number of boys participating in the sports is 15, then how many girls are there in the class ?

A) 20 B) 25
C) 30 D) Data inadequate

Answer:   C) 30

Explanation:

Let the number of boys and girls participating in sports be 3x and 2x respectively.

Then, 3x = 15 or x = 5.

So, number of girls participating in sports = 2x = 10.

Number of students not participating in sports = 60 - (15 + 10) = 35.

Let number of boys not participating in sports be y.

Then, number of girls not participating in sports = (35 -y).

Therefore (35 - y) = y + 5 {\color{Blue} \Leftrightarrow } 2y {\color{Blue} \Leftrightarrow } 30 {\color{Blue} \Leftrightarrow } y = 15.

So, number of girls not participating in sports = (35 - 15) = 20.

Hence, total number of girls in the class = (10 + 20) = 30.

Q:

Difference between two numbers is 5, six times of the smaller lacks by 6 from the four times of the greater. Find the numbers ?

A) 12 & 7 B) 13 & 8
C) 15 & 10 D) 14 & 9
 
Answer & Explanation Answer: A) 12 & 7

Explanation:

x – y = 5

4x – 6y = 6

x = 12 y = 7

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0 4
Q:

The arithmetic mean of the following numbers 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6 and 7, 7, 7, 7, 7, 7, 7 is   ?

A) 6 B) 9
C) 7 D) 5
 
Answer & Explanation Answer: D) 5

Explanation:

Arithmatic mean = sum/members 

=> (1x1 + 2x2 + 3x3 + 4x4 + 5x5 + 6x6 + 7x7) / (1 + 2 + 3 + 4 + 5 + 6 + 7)

=> 140/28 = 5

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1 23
Q:

Thrice the square of a natural number decreased by 4 times the number is equal to 50 more than the number. The number is  ?

A) 5 B) 4
C) 7 D) 6
 
Answer & Explanation Answer: A) 5

Explanation:

Let the number be x. Then,

 - 4x = x + 50

- 5x - 50 = 0

(3x + 10)(x - 5) = 0

x = 5

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1 15
Q:

The sum of three numbers is 98. If the ratio of the first to the second is 2:3. And that of the second to the third is 5:8, then the second number is:

A) 30 B) 27
C) 23 D) 33
 
Answer & Explanation Answer: A) 30

Explanation:

Then, A:B = 2:3 and B:C = 5:8
= (5 x 3/5) : (8 x 3/5) = 3:24/5
A:B:C = 2:3:24/5
= 10:15:24 => B = 98 x 15/49 = 30.

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3 44
Q:

Ajay and Vijay have some marbles with them. Ajay told Vijay "if you give me 'x' marbles, both of us will have equal number of marbles". Vijay then told Ajay "if you give me twice as many marbles, I will have 30 more marbles than you would". Find 'x'  ?

A) 4 B) 10
C) 8 D) 5
 
Answer & Explanation Answer: D) 5

Explanation:

If Vijay gives 'x' marbles to Ajay then Vijay and Ajay would have V - x and A + x marbles.
V - x = A + x --- (1)
If Ajay gives 2x marbles to Vijay then Ajay and Vijay would have A - 2x and V + 2x marbles.
V + 2x - (A - 2x) = 30 => V - A + 4x = 30 --- (2)
From (1) we have V - A = 2x
Substituting V - A = 2x in (2)
6x = 30 => x = 5.

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1 77