# 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 to solve through equations and also 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.

Example :

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

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 Similar to time and work.  In time and work persons will work in Pipes and Cisterns pipes will work.

In time and work total is called units and in  pipes and cisterns 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