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Q:

Pipe A can fill the tank in 4 hours,while pipe B can fill it in 6 hours working separately.pipe C can empty whole the tank in 4 hours. He opened the pipe A and B simultaneously to fill the empty tank. He wanted to adjust his alarm so that he could open the pipe C when it was half-filled, but he mistakenly adjusted his alarm at a time when his tank would be 3/4th filled. what is the time difference between both the cases, to fill the tank fully:

A) 48 min B) 54 min
C) 30 min D) none of these

Answer:   B) 54 min



Explanation:

In ideal Case:

         Time taken to fill the half tank by A and B = \inline \fn_jvn \frac{50}{41.66} =\inline \fn_jvn \frac{6}{5} hours

         Time taken by A,B and C to fill rest half of the tank =\inline \fn_jvn \frac{50}{16.66} = 3 hours

         Total time = \inline \fn_jvn \frac{6}{5}+3 = 4 hours 12 min

In second case:

         Time taken to fill \inline \fn_jvn \frac{3}{4} tank by A and B =\inline \fn_jvn \frac{75}{41.66}=\frac{9}{5} hours

         Time taken by A,B and C to fill rest \inline \fn_jvn \frac{1}{4} tank = \inline \fn_jvn \frac{25}{16.66}=\frac{3}{2} hours

         Total time =\inline \fn_jvn \frac{9}{5}+\frac{3}{2} =3 hours 18 min

Therefore , difference in time = 54 minutes

Q:

Amar can do a piece of work in 10 days. He works at it for 4 days and then Arun finishes it in 9 days. In how many days can Amar and Arun together finish the work ?

A) 4 days B) 8 days
C) 3 days D) 6 days
 
Answer & Explanation Answer: D) 6 days

Explanation:

4/10 + 9/x = 1

=> x = 15

Then both can do in

1/10 + 1/15 = 1/6

=> 6 days

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2 39
Q:

12 men complete a work in 9 days. After they have worked for 6 days, 4 more men join them. How many days will they take to complete the remaining work ?

A) 2 days B) 2.5 days
C) 2.25 days D) 3 days
 
Answer & Explanation Answer: C) 2.25 days

Explanation:

1 man's 1 day work = 1/108
12 men's 6 day's work = 1/9 x 6 = 2/3

Remaining work = 1 - 2/3 = 1/3

16 men's 1 day work = 1/108 x 16 = 4/27
4/27 work is done by them in 1 day.

1/3 work is done by them in 27/4 x 1/3 = 9/4 days.

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2 97
Q:

P alone can complete a piece of work in 6 days. Work done by Q alone in one day is equal to one-third of the work done by P alone in one day. In how many days can the work be completed if P and Q work together  ?

A) 5 (2/3) B) 6 (3/4 )
C) 4 (1/2) D) 3
 
Answer & Explanation Answer: C) 4 (1/2)

Explanation:

Work done by P alone in one day = 1/6th of the total work done by Q alone in one day = 1/3(of that done by P in one day) = 1/3(1/6 of the total) = 1/18 of the total.

Work done by P and Q, working together in one day = 1/6 + 1/18  = 4/18 = 2/9 of the total
 
They would take 9/2 days = 4 (1/2) days to complete the work working together.
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Q:

A can do a piece of work in 30 days. He works at it for 6 days and then B finishes it in 18 days. In what time can A and B together it ?

A) 14 1/2 days B) 11 days
C) 13 1/4 days D) 12 6/7 days
 
Answer & Explanation Answer: D) 12 6/7 days

Explanation:

Let 'B' alone can do the work in 'x' days

6/30 + 18/x = 1
x = 22.5
1/30 + 1/22.5 = 7/90

=> 90/7 = 12 6/7 days

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5 150
Q:

Two persons K and L can complete a piece of work in 30 days and 45 days respectively. If they work together, what part of the work will be completed in 3 days ?

A) 1/6 B) 1/3
C) 2/3 D) 1/18
 
Answer & Explanation Answer: A) 1/6

Explanation:

K's one day's work = 1/30
L's one day's work = 1/45
(K + L)'s one day's work = 1/30 + 1/45 = 1/18

The part of the work completed in 3 days = 3 (1/18) = 1/6.

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