2
Q:

Two boxes contain 4 and 16 balls respectively. Two balls in the first box and four in the second, are black. If a box is chosen randomly and two balls are drawn at random from it, what is the
probability that at least one ball is black if the ball is not replaced?

A) 11/20 B) 43/120
C) 77/120 D) 9/20

Answer:   C) 77/120



Explanation:

At least one black can be chosen in two ways from each box:
Now, probability of choosing at least one black ball from first box 

= 1/2 × [ (2C1× 2C1)/4C2 + 2C2/ 4C2 ]= 5/12

Probability of choosing at least one black ball from 2nd box
= 1/2 × [(4C1×12C1)/16C2 + 4C2/ 16C2] = 9/40

Final probability

= 5/12 + 9/40 = (50 + 27)/120 = 77/120

Q:

Select the odd word/letters/number/number pair from the given alternatives.

A) 81 B) 125
C) 64 D) 198
 
Answer & Explanation Answer: D) 198

Explanation:
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1 338
Q:

Expand and simplify (2x + 5)2 *(4x ­- 1) -­ (3x3 - 16x2 + 25x -­ 21)

A) 13x3 + 92x2 -­ 55x + 4 B) 13x3 -­ 92x2 -­ 55x -­ 4
C) 13x3 + 92x2 + 55x -­ 4 D) 13x3 -­ 92x2 + 55x + 4
 
Answer & Explanation Answer: C) 13x3 + 92x2 + 55x -­ 4

Explanation:
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0 289
Q:

A cone is hollowed out of a solid wooden cube of side 7 cm. The diameter and height of the cone is same as the side of the cube. What is the volume of the remaining cube?

A) 253.17 cubic cms B) 228.84 cubic cms
C) 143.26 cubic cms D) 257.68 cubic cms
 
Answer & Explanation Answer: A) 253.17 cubic cms

Explanation:
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0 270
Q:

Reflection of the point (2,-4) in the origin is

A) (2,4) B) (-2,-4)
C) (2,-4) D) (-2,4)
 
Answer & Explanation Answer: D) (-2,4)

Explanation:
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1 334
Q:

By increasing the price of entry ticket to a fair in the ratio 5:7, the number of visitors to the fair has decreased in the ratio 11:9. In what ratio has the total collection increased or decreased?

A) increased in the ratio 55:63 B) decreased in the ratio 63:55
C) increased in the ratio 45:77 D) decreased in the ratio 77:45
 
Answer & Explanation Answer: A) increased in the ratio 55:63

Explanation:
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0 385
Q:

Asif is twice as good as workman as Bashir and together they finish a piece of work in 30 days. In how many days will Asif alone finish the work?

A) 90 B) 45
C) 60 D) 75
 
Answer & Explanation Answer: B) 45

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0 393
Q:

What smallest number should be added to 2401 so that the sum is completely divisible by 14 ?

A) 8 B) 7
C) 4 D) 5
 
Answer & Explanation Answer: B) 7

Explanation:
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1 421
Q:

What is the altitude of an equilateral triangle whose side is 12 cm?

A) 6√3 cm B) 3√3 cm
C) 6√2 cm D) 4√2 cm
 
Answer & Explanation Answer: A) 6√3 cm

Explanation:
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