Remember Sindhoor’s last article on ‘ How to Prepare for GMAT Verbal Section‘? Here comes his second contribution in the form of a quant article ‘Time and Work’.
Read on:
Problems on Time and Work are a common feature in most of the standard MBA exams. If you are well versed with the basics and have practised these problems during your preparation, they give you an easy opportunity to score and also save time. Here, I will try and give you the basic fundas with the help of examples. Let us start with a very basic problem:
Problem 1: A takes 5 days to complete a piece of work and B takes 15 days to complete a piece of work. In how many days can A and B complete the work if they work together?
Standard Solution: Let us consider Work to be 1 unit. So if W = 1 Unit and A takes 5 days to complete the work then in 1 day A completes 1/5th of the work. Similarly B completes 1/15th of the work.
If they work together, in one day A and B can complete (1/5 + 1/15 = 4/15) of the work. So to complete 1 unit of work they will take 15/4 days.
New method: Let us assume W = 15 units, which is the LCM of 5 and 15.
Given that total time taken for A to complete 15 units of work = 5 days
–> A’s 1 day work = 15/5 = 3 units
Given that total time taken for B to complete 15 units of work = 15 days
–> B’s 1 day work = 15/15 = 1 unit
–>(A + B)’s 1 day work = 3 + 1 = 4 units
–>15 units of work can be done in 15/4 days.
Many solve Time and Work problems by assuming work as 1 unit (first method) but I feel it is faster to solve the problems by assuming work to be of multiple units (second method). This would be more evident when we solve problems which are little more complex than the above one.
Problem 2: X can do a work in 15 days. After working for 3 days he is joined by Y. If they complete the remaining work in 3 more days, in how many days can Y alone complete the work?
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Time and Work: http://totalgadha.com/mod/forum/discuss.php?d=5551
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