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Home Aptitude Time and Work Comments

  • Question
  • K can build a wall in 30 days. L can demolish that wall in 60 days. If K and L work on alternate days, when will the wall be completed ?


  • Options
  • A. 120 days
  • B. 119 days
  • C. 118 days
  • D. 117 days

  • Correct Answer
  • 117 days 

    Explanation

    K's work in a day(1st day) = 1/30
    L's work in a day(2nd day)= -1/60(demolishing)
    hence in 2 days, combined work= 1/30 - 1/60 =1/60
    since both works alternatively, K will work in odd days and L will work in even days.
    1/60 unit work is done in 2 days
    58/60 unit work will be done in 2 x 58 days = 116 days
    Remaining work = 1-58/60 = 1/30
    Next day, it will be K's turn and K will finish the remaining 1/30 work.
    hence total days = 116 + 1 = 117.

  • Tags: GATE, CAT, Bank Exams, AIEEE, Bank PO, Bank Clerk

    Time and Work problems


    Search Results


    • 1. One girl can eat 112 chocolates in half a minute, and her boy friend can eat half as many in twice the length of time. How many chocolates can both boy and girl eat in 12 seconds ?

    • Options
    • A. 44
    • B. 32
    • C. 56
    • D. 49
    • Discuss
    • 2. A certain job was assigned to a group of women to do it in 20 days. But 12 women did not turn up for the job and the remaining did the job in 32 days. The original number of women in the group was?

    • Options
    • A. 36
    • B. 32
    • C. 22
    • D. 28
    • Discuss
    • 3. If a soldier fires 7 shots from a gun in 12 minutes then find the total number of shots fired by the man in 3/2 hrs.

    • Options
    • A. 45
    • B. 44
    • C. 46
    • D. 47
    • Discuss
    • 4. Two persons Shyam and Rahim can do a job in 32 days together. Rahim can do the same job in 48 days alone. They started working together and after working 8 days Rahim is replaced by a third person Ram whose efficiency is half that of Rahim. Find in how many days the remaining work will be completed by both Shyam and Ram together?

    • Options
    • A. 16 days
    • B. 72/5 days
    • C. 15 days
    • D. 96/5 days
    • Discuss
    • 5. In a public bathroom there are n taps 1,2,3...n. Tap1 and Tap2 take equal time to fill the tank while Tap3 takes half the time taken by Tap2 and Tap4 takes half the time taken by Tap3. Similarly each next number of tap takes half the time taken by previous number of Tap i.e, K-th Tap takes half the time taken by (K-1)th Tap. If the 10th tap takes 2 hours to fill the tank alone then what is the ratio of efficiency of 8th tap and 12th tap, respectively?

    • Options
    • A. 4:1
    • B. 5:3
    • C. 16:1
    • D. 1:16
    • Discuss
    • 6. Five men and nine women can do a piece of work in 10 days. Six men and twelve women can do the same work in 8 days. In how many days can three men and three women do the work ?

    • Options
    • A. 18 days
    • B. 20 days
    • C. 16 days
    • D. 14 days
    • Discuss
    • 7. Amar can do a piece of work in 10 days. He works at it for 4 days and then Arun finishes it in 9 days. In how many days can Amar and Arun together finish the work ?

    • Options
    • A. 4 days
    • B. 8 days
    • C. 3 days
    • D. 6 days
    • Discuss
    • 8. A, B and C can do a piece of work in 72, 48 and 36 days respectively. For first p/2 days, A & B work together and for next ((p+6))/3days all three worked together. Remaining 125/3% of work is completed by D in 10 days. If C & D worked together for p day then, what portion of work will be remained?

    • Options
    • A. 1/5
    • B. 1/6
    • C. 1/7
    • D. 1/8
    • Discuss
    • 9. Lasya alone can do a work in 16 days. Srimukhi?s efficiency is 20 % lesser than that of Laya. If Rashmi and Srimukhi together can do the same work in 12 days, then find the efficiency ratio of Rashmi to that of Lasya?

    • Options
    • A. 19 : 7
    • B. 30 : 19
    • C. 8 : 15
    • D. 31 : 17
    • Discuss
    • 10. Sharan and Mayukh, working together, can complete a task in 18 days. However, Mayukh works alone and leaves after completing 1/3 of the task. Then, Sharan takes over and completees the remaining work by himself. As a result, the duo could complete the task in 40 days. How many days would Sharan alone have taken to do the job if Mayuk' had worked faster than Sharan ?

    • Options
    • A. 24
    • B. 45
    • C. 72
    • D. 30
    • Discuss


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