SSC is known for the recruitment of Group ‘B’ and ‘C’ posts under several ministries/departments in the Government of India. SSC organizes various examinations like SSC CGL, CHSL, Stenographer, and for SI/DP/CAPF, etc., throughout the year with the same exam pattern, But different difficulty level. Questions from this topic are mainly based on work, time, pipes, and cisterns. You will get nearly 2-3 questions out of this topic in every SSC exam.
In this article, we will discuss the tips and concepts, which are useful in solving questions hailed from time & work topic. Let us go through it-
SSC Quantitative Tips: Pipe and cisterns
Pipes and cisterns problems are similar to time and work problem, the only difference is that pipes and cisterns problems have outlets and inlets.
Condition 1: Inlet is a pipe connected to a tank, which fills it
Condition 2: The outlet is a pipe connected to a tank to empty it.
Mathematical use:-
Both the pipes are opened, then the net part filled in 1 hour =
=> Time taken to fill the tank =
Example 1: How much time will it take to fill the tank if a pipe A fill it in 30 hours and another pipe B empties it in 40 hours?
Solution: Net part filled in 1 hour =
Hence, the time is taken to fill the tank = 12 hours.
Direct method:
The time is taken to fill the tank=
Condition 3: If two pipes fill the tank in x and y hours respectively, then the net part filled in 1 hour, when both the pipes are opened =
=> time is taken to fill the tank =
Example 2: How much time will it take to fill the tank, if two pipes A and B fill it in 20 hours and 30 hours respectively and both the pipes are opened?
Sol 2: Net part filled by both pipes A and B together in 1 hour =
Hence, the time taken to fill the tank is 12 hours.
Direct method:
The time is taken to fill the tank=20*30/30+20=600/50= 12 hrs.
Condition 4: If two pipes fill the tank In x and y hours, respectively, and a third pipe emptied the complete filled tank in z hours, then the net part filled in 1 hours, when all the pipes are opened =
=> time is taken to fill the tank =
Example3: How much time will it take to fill the tank if two pipes A and B fill it in 10 hours and 20 hours respectively and a third pipe C empties it in 40 hours?
Solution: Net part filled in 1 hour=
Hence, the time is taken to fill the tank = 8 hours.
Direct method:
The time is taken to fill the tank
Condition 5: If a pipe fills the tank in x hours but due to leakage in the bottom it is filled in y hours, then the time is taken by a leak to empty the tank if the tank is full
Example 4: How much time will the leak take to empty the tank if a pipe A fill it in 10 hours but due to leak in the bottom it is filled in 15 hours?
Solution: Tank empty due to leak in 1 hour=
Hence, the leak will empty the full tank in 30 hours;
Direct method:-
The required time,
Practice Questions from various exams
1. A and B together can complete a task in 20 days. Band together can complete the same task in 30 days. A and C together can complete the same task in 40 days. What is the respective ratio of the number of days taken by A when completing the same task alone to the number of days taken by C when completing the same task alone?
Solution: Since A and B can finish the work in 20 days. Then, A and B’s one day’s work =1/20
Since B and C can finish the work in 30 days. Then, B and C’s one day’s work =1/30
Since A and C can finish the work in 40 days. Then, A and C’s one day’s work = 1/40
Adding we get 2(A + B + C)’s one day’s work
(A + B + C)’s one day’s work = 13/240
A’s one day’s work
Hence, A alone can finish the work in 48 days.
C’s one day’s work
Hence, C alone can finish the work in 240 days.
Required Ratio=48/240 =1:5;
Ans: (d)
2. Seven girls can do a piece of work in 13 days, six boys can do the same piece of work in 12 days, nine men can do the same piece of work in nine days and six women can do the same piece of work in 14 days. Who is the most efficient?
Solution: One girl can complete the work in 7 ⤬ 13 = 91 days.
One boy can complete the work in 6 ⤬ 12 = 72 days.
One man can complete the work in 9 ⤬ 9 = 81 days.
One woman can complete the work in 6 ⤬ 14 = 84 days.
Hence, boys are the most efficient.
Ans: (a)
3. A can do a piece of work in 70 days and B is 40% more efficient than A. The number of days taken by B to do same amount of work is.
Solution: A can do a piece of work in 70 days, while B is 40% more efficient than A.
Hence, B do the same work in= 70 x 100/140= 70 x 5/7= 50 days.
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