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Q:

What is the product of all the numbers in the dial of a telephone ?

A) 1,58,480 B) 1,59,450
C) 1,59,480 D) None of these

Answer:   D) None of these

Explanation:

Since one of the numbers on the dial of a telephone is zero, so the product of all the numbers on it is 0.

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 22
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 75
Q:

O and O' are the center of the two circles with radii 7cm and 9cm respectively. The distance between the centers is 20cm. If PQ be the transverse common tangent to the circles, which cuts OO' at X, what is the length of O'X in cm ?

A) 10 B) 6
C) 35/4 D) 45/4
 
Answer & Explanation Answer: D) 45/4

Explanation:

As clear from the figure itself, triangle OQX and triangle O'PX are similar.

So,

OQ/O'P = OX/O'X

=> OX = (7/9)xO'X

And since, OX + O'X = 20

=> (7/9)xO'X + O'X = 20

=> O'X = 45/4

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1 109