Tropical Deciduous Forest |  Sectors of Indian Economy |  How Legislative Council is Formed |  Insectivorous Plants |  Causes of Revolt of 1857 in Points |  Ordinance Making Power of President and Governors |  Mangroves Cover in India |  Coral Reefs in India |  Seasons and Climate in India |  Constitutional and Statutory Bodies in India |  Rock Edicts of Ashoka |  Types of Motions in Parliamentary Procedure |  Types of Majorities in Parliament |  Pressure Groups in World and India |  Order of Precedence |  Types of Rocks |  Treaties in Indian History |  Types of Rocks |  Features of Indian Economy |  Geographical Indications |  Ancient History Terminology and Meanings |  Schedules of the Constitution |  Nuclear Power Plants in India List  |  Types of Clouds for SSC CGL | Nuclear Power Plants in India ListTypes of Ocean CurrentsStructure: Layers of EarthAPPSC Group 1 Answer KeySSC JE 2017 QUESTION PAPEROne Word Substitution for SSC and Bank ExamsMPSC Answer Key 2017 2017Layers of AtmosphereMPSC Answer Key 2017 2017BPSC Solved Question Paper 2017MPPSC Solved Question Paper 2017GST Bill IndiaDelhi SultanateLaw Commission of IndiaOscar Awards Winner 2017 ListDiseases in CropsCommon Drugs and UsesDifferent Types of Deserts in WorldUPSC Civil Services Exam-2016 Answer KeyUPSC CAPF Exam-2016 Answer Key | UPPSC UPPER Subordinate Exam-2016 Answer Key | Regulatory BodiesNational Parks in India | International Airports in India  | United Nation International Years National Highways | National Birds of Countries | Sessions of Congress  | Facts About Kerala

Time & Work

·       Time and Work problems are the prime example of indirect proportion. As we all know that if number of persons are increased then time taken to complete a given work would decrease. In indirect proportion when one variable is increase other would automatically decreased and vice-versa.
·       In this chapter we will all types of problems asked in examination one by one through examples.

Points to Remember:
·       Inverse of the work done in one will give the total time require to complete that work. Hence our primary aim would be to find out work done in one day.
·       If A is twice efficient as B than the ratio of their work done will A: B = 2:1 and so on.

  A take 5 days to complete a job and B takes 10 days to complete the same job. In how much time they will complete the job together?

            Work done by A in one day = 1/5
            Work done by B in one day = 1/10
            Work done by both together in one day = 1/5 + 1/10
                                                                          = 3/10
            Since inverse of work one in one day gives total time to complete the given job
            Hence, total time taken to complete the job when working together = 10/3 = 3.333 Days.

A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is ?

            Work done by A in one day = 1/15
            Work done by B in one day = 1/20
            One done in one day when working together = 1/15 + 1/20
                                                                                    = 7/60
            Since they work together for 4 days ,
            Work done in 4 days when working together = 4×7/60
                                                                                    = 7/15
            Fraction of work left = 1- work completed
                                            = 1- 7/15
                                            = 8/15

A is twice as good a workman as B and together they finish a piece of work in 14 days. A alone can finish the work in?

            Since A is Twice good as B, Hence ratio of work done of A & B = 2:1
            Let, Work done by A alone in one day = x
            Therefore, work done by B alone in one day would be = x/2
            Work done in one day when working together = x + x/2
                                                                              = 3x/2
            Time taken in completing the work = 2/3x = 14(given)
            A alone can finish the work in 21 Days.

A and B can do piece of work in 12 days; B and C in 15 days; C and A in 20 days. A alone can do the work in?

            One day work of
                                    A+B =1/12
                                    B+C = 1/15
                                    C+A = 1/20
Formula to get one day work of A = ½ [ one day work of (A+B) +one day work of (A+C) - one day work of (B+C) ]
     =1/2 [ 1/12  + 1/15  -1/20 ]
                                                = 1/30
Hence A alone can finish work in 30 days

A and B can do a work in 8 days, B and C can do the same work in 12 days. A, B and C together can finish it in 6 days. A and C together will do it in ?

One day work of
                        A+B = 1/8 ……..(1)
                        B+C = 1/12 …….(2)
                    A+B+C = 1/6 …….(3)
     2×Eqn(1) – [Eqn (2) + Eqn (1)]

This will give work done in one day by A & C together = 1/8

Hence, Time taken by A & C to complete the work = 8 days.

Related Posts