Newton, Einstein, and Tesla working alone can do a piece of work in 20, 30, and 60 days respectively. All three of them start the work together, but after x days Newton leaves and then after y more days Einstein leaves and Tesla completes the remaining work. If Einstein had not left, Tesla and Einstein would have completed the remaining work in (y + 6) days after Newton had left. If both Newton and Einstein had stayed, the work would have been completed in (x + 6) days. What is the total number of days taken to complete the work?
Newton, Einstein, and Tesla working alone can do a piece of work in 20, 30, and 60 days respectively. All three of them start the work together, but after x days Newton leaves and then after y more days Einstein leaves and Tesla completes the remaining work. If Einstein had not left, Tesla and Einstein would have completed the remaining work in (y + 6) days after Newton had left. If both Newton and Einstein had stayed, the work would have been completed in (x + 6) days. What is the total number of days taken to complete the work? Correct Answer 28
Given:
Newton’s Time = 20 days
Einstein’s Time = 30 days
Tesla’s Time = 60 days
All three together time = (x + 6) days
Calculation:
The data provides three different combinations of working, to do the work completely.
1) Combination 1 -
All three people working for(x+6) days.
(1/20 + 1/30 + 1/60) = 1/(x + 6)
⇒ (6/60) = 1/(x + 6)
⇒ x + 6 = 10
⇒ x = 4 days
2) Combination 2 -
All three people for x days,and two people for(y + 6) days.
(x)/10 + (y + 6)(1/30 + 1/60) = 1
Substituting x=4,
⇒ 4/10 + (y + 6)(1/20) = 1
⇒ (y + 6)(1/20) = 1 – 4/10
⇒ y + 6 = 12
⇒ y = 6
3) Combination 3 –
All three for x days, two people for y days and one person for z days.
x(1/10) + y(1/20) + z/60 = 1
Substituting x=4,y = 6, and simplifying,
⇒ z/60 = 1 – 4/10 –6/20
⇒ z/60 = 3/10
⇒ z = 18 days
∴ Total number of days required under combination 3, is
x + y + z = 4 + 6 + 18 = 28 days
Alternate Method –
1. A, B and C four days work = 4 × 6 = 24
Left work = 60 - 24 = 36
(B + C) complete left work in Time = 36/3 = 12
Y + 6 = 12
Y = 6
2. (B + C) 6 days work 6 × 3 = 18
work left = 60 – 24 – 18 - 18
C = 18 /1 =18 days
Total time = A + B + C = 4 + 6 = 28 days
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