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Q:

Three taps A,B and C can fill a tank in 12,15 and 20 hours respectively. If A is open all the time and B ,C are open for one hour each alternatively, the tank will be full in:

A) 6 hrs	B) 20/3 hrs
C) 7 hrs	D) 15/2 hrs

Answer & Explanation Answer: C) 7 hrs

Explanation:

$(A + B)' s 1 h o u r w o r k = (\frac{1}{12} + \frac{1}{15}) = \frac{9}{60} = \frac{3}{20}$

$(A + C)' s 1 h o u r w o r k = (\frac{1}{12} + \frac{1}{20}) = \frac{8}{60} = \frac{2}{15}$

$p a r t f i l l e d i n 2 h r s = (\frac{3}{20} + \frac{2}{15}) = \frac{17}{60}$

$p a r t f i l l e d i n 6 h r s = (3 * \frac{17}{60}) = \frac{17}{20}$

$r e m a i n i n g p a r t = (1 - \frac{17}{20}) = \frac{3}{20}$

Now, it is the turn of A and B (3/20) part is filled by A and B in 1 hour.

Therefore, Total time taken to fill the tank =(6+1)hrs= 7 hrs

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Filed Under: Pipes and Cistern

Q:

One pipe can fill a tank three times as fast as another pipe. If together the two pipes can fill the tank in 36 min, then the slower alone will be able to fill the tank in:

A) 81 min	B) 108 min
C) 144 min	D) 192 min

Answer & Explanation Answer: C) 144 min

Explanation:

Let the slower pipe alone fill the tank in x minutes.

Then,faster pipe will fill it in x/3 minutes.

$= > \frac{1}{x} + \frac{3}{x} = \frac{1}{36} = > \frac{4}{x} = \frac{1}{36} = > x = 144 m i n s$

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Filed Under: Pipes and Cistern

Q:

If $a = \frac{\sqrt{5} + 1}{\sqrt{5} - 1} b = \frac{\sqrt{5} - 1}{\sqrt{5} + 1} t h e n f i n d t h e v a l u e o f [\frac{a^{2} + a b + b^{2}}{a^{2} - a b + b^{2}}] i s : :$

A) 3/4	B) 4/3
C) 3/5	D) 5/3

Answer & Explanation Answer: B) 4/3

Explanation:

By simplifying, we get 4/3

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Filed Under: Square Roots and Cube Roots
Exam Prep: AIEEE , Bank Exams , CAT
Job Role: Bank Clerk , Bank PO

Q:

If x = $7 - 4 \sqrt{3} t h e n f i n d t h e v a l u e o f (x + \frac{1}{x}) ?$

A) 3sqrt{3}	B) 8sqrt{3}
C) 14	D) 14+8sqrt{3}

Answer & Explanation Answer: C) 14

Explanation:

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Filed Under: Square Roots and Cube Roots
Exam Prep: Bank Exams , CAT
Job Role: Bank Clerk , Bank PO

Q:

$\frac{3 + \sqrt{6}}{5 \sqrt{3} - 2 \sqrt{12} - \sqrt{30} + \sqrt{50}} = ?$

A) 3	B) 3sqrt{2}
C) 6	D) None of these

Answer & Explanation Answer: D) None of these

Explanation:

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Filed Under: Square Roots and Cube Roots
Exam Prep: AIEEE , Bank Exams , CAT
Job Role: Bank Clerk , Bank PO

Q:

If $\frac{5 + 2 \sqrt{3}}{7 + 4 \sqrt{3}} = a + b \sqrt{3} t h e n a & b = ?$

A) a=-11,b=-6	B) a=-11,b=6
C) a=11,b=-6	D) a=11,b=6

Answer & Explanation Answer: C) a=11,b=-6

Explanation:

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Filed Under: Square Roots and Cube Roots
Exam Prep: AIEEE , Bank Exams , CAT
Job Role: Bank Clerk , Bank PO

Q:

$[\frac{3 \sqrt{2}}{\sqrt{6} - \sqrt{3}} - \frac{4 \sqrt{3}}{\sqrt{6} - \sqrt{2}} - \frac{6}{\sqrt{8} - \sqrt{12}}] = ?$

A) sqtr{3}-sqrt{2}	B) sqtr{3}+sqrt{2}
C) 5sqrt{3}	D) 1

Answer & Explanation Answer: C) 5sqrt{3}

Explanation:

Given Exp = $\frac{3 \sqrt{2}}{\sqrt{6} - \sqrt{3}} \times \frac{\sqrt{6} + \sqrt{3}}{\sqrt{6} + \sqrt{3}} - \frac{4 \sqrt{3}}{\sqrt{6} - \sqrt{2}} \times \frac{\sqrt{6} + \sqrt{2}}{\sqrt{6} + \sqrt{2}} - \frac{6}{2 (\sqrt{2} - \sqrt{3})}$

= $\frac{3 \sqrt{2} (\sqrt{6} + \sqrt{3})}{6 - 3} - \frac{4 \sqrt{3} (\sqrt{6} + \sqrt{2})}{6 - 2} + \frac{3}{(\sqrt{3} - \sqrt{2})} \times \frac{(\sqrt{3} + \sqrt{2})}{(\sqrt{3} + \sqrt{2})}$

= $\sqrt{2} (\sqrt{6} + \sqrt{3}) - \sqrt{3} (\sqrt{6} + \sqrt{2}) + 3 (\sqrt{3} + \sqrt{2})$

= $\sqrt{12} + \sqrt{6} - \sqrt{18} - \sqrt{6} + 3 \sqrt{3} + 3 \sqrt{2}$

= $5 \sqrt{3}$

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Filed Under: Square Roots and Cube Roots

Q:

If 3a=4b=6c and $a + b + c = 27 \sqrt{29}$ , then $\sqrt{a^{2} + b^{2} + c^{2}} = ?$

A) 81	B) 83
C) 87	D) None of these

Answer & Explanation Answer: C) 87

Explanation:

$4 b = 6 c \Rightarrow b = \frac{3}{2} c a n d 3 a = 4 b \Rightarrow a = \frac{4}{3} b = \frac{4}{3} (\frac{3}{2} c) = 2 c$

$a + b + c = 27 \sqrt{29} \Rightarrow 2 c + \frac{3}{2} c + c = 27 \sqrt{29} \Rightarrow c = 6 \sqrt{29}$

$∴ \sqrt{a^{2} + b^{2} + c^{2}} = \sqrt{(a + b + b)^{2} - 2 (a b + b c + c a)}$

$= \sqrt{(27 \sqrt{29})^{2} - 2 (2 c \times \frac{3}{2} c + \frac{3}{2} c \times c + c \times 2 c)}$

$= \sqrt{(729 \times 29) - 2 \times \frac{13}{2} c^{2}}$

= 87

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Filed Under: Square Roots and Cube Roots

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