Compilation - Time and Work (Under development)

Types of problems

Type 1

Father son wife problem. aim is to find final timr taken by single person to do the job. trick is to find the ratio of the given quantities and then substitute it in the formula where variables will cansel out.

Type 2

multiple persons set out to perform a task. but some people always leave and some are added on the go.

trick to solve these question is to get individual unit of work performed and then add them all up.

pipes and cistern follows the same logic except when water is leaking the unit work is considered negative.

also rate of flow is directly proportional to diameter square in case of pipes.

other variant of pipes include on in which the container capacity needs to be found, in this case rate of flow will be given.

Type 3 

garrison issue type; in these questions food (for instance) will be sufficient for certain period and a condition will be given in whic some people will die/leave and time period will be asked .

these are based on manhour concept. a total work is divided into smaller work with different number of peoples

in order to form the formula, take time on rhs and take value on lhs and try to answer if time will decrease/increase if the value is increased and determine the relation aa direct or indirect.

Type 4

pattern problem. in these type a person gets help from others in some pattern. or couple of person followattern to complete a job.

and final day on which the work gets completed needs to be determined. trick is to club the whole pattern as one and repeat it until the job gets completed i.e. just before the ratio increase by 1. then take few minor steps determine final time required.

The pattern can also be triplet or quad, where each member will perform task  #un-1#cuC#lr-1#cl.

Type 5

share in income is given by the amount of work completed by person usually in one day.

1/(time taken to complete full job)

Type 6

product constancy. in the middle of project a person remembers that the project will extend and overshoot by some percentage (lesser work will be done, which means project will overshoot.)

a new person is caled and project is completed on time. the work performed by new person is in relaton with the work performed by previous employees. this is used to find the period required to do the job.

Type

GP problem. in these problem we'll be given condition that efficiency reduces continously. This forms a GP and we need to find the days required to complete the job. which is done by using summation formula.

Tip

the work is the lcm of all the people and their individual contribution is days required/lcm.

using this you'll reach solution quicker.