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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 & Explanation 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

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Filed Under: Quantitative Aptitude - Arithmetic Ability
Exam Prep: Bank Exams , GATE

Q:

Train A, travelling at 84 kmph, overtook train B, traveling in the same direction, in 10 seconds. If train B had been traveling at twice its speed, then train A would have taken 22.5 seconds to overtake it. Find the length of train B, given that it is half the length of train A.

A) 180 m B) 100 m
C) 200 m D) 150 m
 
Answer & Explanation Answer:

Explanation:

Let speed of train B be x m/s And length of train B be y m
Then length of train A is 2y m
Speed of train A = 84 × 5/18 = 210/9 m/s = 70/3 m/s
A.T.Q, (2y+y)/10 = 70/3 − x .............(i)
and (2y+y)/ 22.5 = 70/3 − 2x ................(ii)
solving (i) and (ii), y = 50 m

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Filed Under: Quantitative Aptitude - Arithmetic Ability
Exam Prep: Bank Exams , GATE

Q:

Type 1 workers can do three times the work of Type 2 workers. Twelve Type 1 workers can complete a task in 10 days. How many days would it have taken 4 Type 1 and 8 Type 2 workers to complete the same task?

A) 16 B) 17
C) 20 D) 18
 
Answer & Explanation Answer: D) 18

Explanation:
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Filed Under: Time and Work
Exam Prep: AIEEE , Bank Exams , CAT

Q:

A solid sphere of radius 6 cm is melted and re-casted into a hollow cylinder of uniform thickness. If the external radius of the base of the cylinder is 5 cm and its height is 32 cm, find the uniform thickness of the cylinder ?

A) 3 cm B) 1.5 cm
C) 1 cm D) 2.5 cm
 
Answer & Explanation Answer: C) 1 cm

Explanation:

Let, inner radius of cylinder be ‘x’ cm.
4/3 π(6)3 = π × 32 (52 − x2)

or, (4 × 6 × 6 × 6) / (3 × 32) = 25 − x2 or, x2 = 25 − 9
or, x = 4 cm
Hence, thickness = 5 – 4 = 1 cm.

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Filed Under: Quantitative Aptitude - Arithmetic Ability
Exam Prep: Bank Exams , GATE

Q:

Consider the given question and decide which of the following statements is/are sufficient to answer the question.

Is X-5 even? X is a real number.

Statements :

1. X-15 belongs to integer

2. X-10 is an odd integer

A) Statement 1 alone is sufficient while sufficient 2 alone is insufficient B) Neither sufficient 1 nor 2 is sufficient
C) Statement 2 alone is suuficient while sufficient 1 alone is insufficient D) Both statements 1 and 2 are sufficient
 
Answer & Explanation Answer: B) Neither sufficient 1 nor 2 is sufficient

Explanation:
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Filed Under: Statement and Conclusions
Exam Prep: AIEEE , Bank Exams , CAT

Q:

X and Y entered into partnership with Rs. 700 and Rs. 600 respectively. After another 3 months, X withdrew two- sevenths of his stock but after 3 months, he puts back three-fifths of what he had withdrawn. The total profit at the end of the year is Rs. 726. How much of this should X receive?

A) Rs. 336 B) Rs. 366
C) Rs. 633 D) Rs. 663
 
Answer & Explanation Answer: B) Rs. 366

Explanation:

Profit ratio X & Y = (700 × 3) + (700 × 5/7× 3) + (700× 5/7 + 200 × 3/5 )× 6 : 600 ×12
X:Y= 7320 : 7200= 183:180
∴ X’s share from profit = 183 × 726/(183+180) = Rs. 366.

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Filed Under: Quantitative Aptitude - Arithmetic Ability
Exam Prep: Bank Exams , GATE

Q:

The SI unit of resistance is:

A) Newton B) Coulomb
C) Ohm D) Joule
 
Answer & Explanation Answer: C) Ohm

Explanation:
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Filed Under: Physics
Exam Prep: AIEEE , Bank Exams , CAT

Q:

A ladder 13 m long reaches a window which is 12 m above the ground on side of a street. Keeping its foot at the same point, the ladder is turned to the other side of the street to each a window 5m high, then the width of the street is :

A) 17 m B) 16 m
C) 14 m D) 15 m
 
Answer & Explanation Answer: A) 17 m

Explanation:
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Filed Under: Height and Distance
Exam Prep: Bank Exams