Question 1

What is the verified answer to “Solve this Time and Work question: 15 identical machines working 6 hours daily for 20 days produce 10 units. How many machines are required to produce 25 units in 25 days while working 10 hours daily?”?

Accepted Answer

18 machines, option A.

Question 2

Which method solves this Time and Work item?

Accepted Answer

Rebuild and verify the complete work-rate equation.

Question 3

Why are the other options incorrect?

Accepted Answer

17 machines, 19 machines, 20 machines break a clue, direction, transition or operation.

Question 4

How should the answer be checked?

Accepted Answer

Replay the rule from the first clue or term and test every intermediate step.

Question 5

What is Time and Work and what is the basic concept?

Accepted Answer

Time and Work problems involve finding how long it takes to complete a task. Basic concept: If A can do a work in n days, A's one day work = 1/n. If A and B together can do work in n days, combined one day work = 1/n. Key formula: Total Work = Efficiency x Time. Time and Work is a major topic in SSC CGL, IBPS Bank PO, SBI PO, CAT, and Railway exams.

Question 6

How to solve Time and Work problems using LCM method?

Accepted Answer

LCM Method: Assume total work = LCM of given days. Calculate each person's work per day = Total work divided by Days. Combined work per day = Sum of individual work rates. Time = Total work divided by Combined rate. Example: A can do work in 10 days, B in 15 days. LCM(10,15) = 30 units. A's daily work = 3 units, B's = 2 units. Together = 5 units/day. Time = 30/5 = 6 days. This avoids fractions and is much faster.

Question 7

How to solve problems when people join or leave work midway?

Accepted Answer

When worker joins midway: Find work done before and after they join. If A works for x days and B joins for y days, Total work = A's work in x days + (A+B)'s work in y days. Example: A alone in 20 days. If A works 6 days then B joins, to find when work completes: A's 6 days work = 6/20 = 3/10. Remaining = 7/10. If A+B together rate = 1/12, days to finish = (7/10)/(1/12) = 8.4 days.

Question 8

What are Pipes and Cistern problems in Time and Work?

Accepted Answer

Pipes and Cistern: Inlet pipe fills cistern (positive), Outlet pipe empties cistern (negative). If inlet fills in x hours, rate = 1/x per hour. If outlet empties in y hours, rate = 1/y per hour. Net rate = 1/x - 1/y. Time to fill = xy/(y-x) hours if y > x. Cistern fills if net rate is positive. These problems are standard in IBPS, SBI, and SSC competitive exams.

Question 9

What is work equivalence and efficiency in Time and Work problems?

Accepted Answer

Work Equivalence: Men x Days = Women x Days (when efficiency ratio is known). If 1 man = 2 women in efficiency, then 10 men = 20 women. Men-Days concept: 10 men x 5 days = 50 man-days. If 8 men do same work, days = 50/8 = 6.25 days. For wages: divide total payment in ratio of work done. If A and B complete work together and A worked fewer days, calculate individual shares accordingly.

Solve this Time and Work question: 15 identical machines working 6 hours daily for 20 days produce 10 units. How many machines are required to produce 25 units in 25 days while working 10 hours daily?

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