12
Q:

# Two pipes A and B can fill a tank in 24 hours and $\inline \frac{120}{7}$ hours respectively. Harihar opened the pipes A and B to fill an empty tank and some times later he closed the taps A and B , when the tank was supposed to be full. After that it was found that the tank was emptied in 2.5 hours because an outlet pipe "C" connected to the tank was open from the beginning. If Harihar closed the pipe C instead of closing pipes A and B the remaining tank would have been filled in :

 A) 2 hours B) 8 hours C) 6 hours D) 4 hours

Explanation:

Efficiency of Inlet pipe A = 4.16%                              $\inline (\frac{100}{24})$

Efficiency of Inlet pipe B = 5.83%                              $\inline (\frac{100}{120/7})$

$\inline \therefore$ Efficiency of A and B together = 100 %

Now, if the efficiency of outlet pipe be x% then in 10 hours the capacity of tank which will be filled = 10 *  (10 - x)

Now, since this amount of water is being emptied by C at x% per hour, then

$\inline \frac{10\times (10-x)}{x}=2.5 \: hours \Rightarrow$ x = 8%

Therefore, in 10 hours 20% tank is filled only. Hence, the remaining 80% of the  capacity will be filled by pipes A and B  in 80/10 = 8 hours

Q:

K can lay Highway road between two cities in 16 days. L can do the same job in 12 days. With the help of M, they completes the job in 4 days. How much days does it take for M alone to complete the work ?

 A) 47/7 days B) 59/6 days C) 48/5 days D) 57/5 days

Explanation:

Amount of work K can do in 1 day = 1/16

Amount of work L can do in 1 day = 1/12

Amount of work K, L and M can together do in 1 day = 1/4

Amount of work M can do in 1 day = 1/4 - (1/16 + 1/12) = 3/16 – 1/12 = 5/48

=> Hence M can do the job on 48/5 days = 9 (3/5) days

2 36
Q:

After working for 8 days, Hari Ram finds that only 1/3 rd of the work has been done. He employs Satya who is 60% as efficient as Hari Ram. How many days more would Satya take to complete the work ?

 A) 24 1/2 days B) 25 3/2 days C) 24 2/3 days D) 26 2/3 days

Explanation:

1/3 ---- 8

1 -------?
Hari can do total work in = 24 days

As satya is 60% efficient as Hari, then

Satya = 1/24 x 60/100 = 1/40

=> Satya can do total work in 40 days

1 ----- 40

2/3 ---- ? => 26 2/3 days.

5 144
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

Explanation:

4/10 + 9/x = 1

=> x = 15

Then both can do in

1/10 + 1/15 = 1/6

=> 6 days

2 125
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

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.

2 149
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