Aptitude Chapter-12

Bodhak competitive bank exam time work in this chapter we will discuss Time and Work, Pipes and Cisterns, Number system. We will see how o solve through equations and through shortcut methods.

Time and Work:

A can do a piece of work in x days then A’s one day work is 1/x.

B can do a piece of work in y days then B’s one day work is 1/y.



competitive bank exam time & work

A and B one day work is 1/x + 1/y

If C’s one day work is 1/z then he can complete the work in z days.

an example quotation:

A can do a piece of work in 20 days, B can do the same work 30 days then A and B together can complete the work in how many days?

Solution : We can solve the above problem in 2 methods.

Method 1:  A=20  —–> 1/20

B=30 —–> 1/30

A + B = (1/20)+(1/30) = 5/60=1/12

Answer is 12 Days.

Method 2: L.C.M method or  units method

A = 20,  B=30

Step 1:  Find L.C.M of 20,30  i.e   2,3

10X2X3 = 60

So 60 is called units.

A = 60 units/20 days = 3 units per days

B = 60 units/30 days = 2 units per days

A + B = 3 + 2 = 5 units per day

so 60/5 = 12 days


Pipes and Cisterns:

Pipes and Cisterns are same as time and work. Their men will work here pipes will work. Their total is called units and here total is called liters.

Two pipes A and B can fill a tank in 36 and 45 hours respectively. If both the pipes are opened simultaneously, how much time they take to fill the tank?

Number System:

The L.C.M (Least Common multiple) of 20,30 is

10X2X3 = 60

The H.C.F (Highest Common Factor) of 20,30 is

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