Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

A contractor has to finish a contract of laying drainage [#permalink]
17 Aug 2004, 14:04

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

A contractor has to finish a contract of laying drainage pipes in 80 days, for which he requires 240 men. But when it rains, workers can work only with 50% efficiency. To compensate, the company allots one more day to complete the work, provided it rains for 4 days. In the whole project, it rains for 16 days. How many more days will he take than the allotted time to complete the work?

12 days
since there are 16 raining days and workers are at 50% of capacity then, it will take an extra 16 days to finish job. But for every 4 rainy days, there is another 1 day recuperated. Hence, 16-4=12 days extra. Is it me or all the rest of the info is just extraneous? _________________

12 days since there are 16 raining days and workers are at 50% of capacity then, it will take an extra 16 days to finish job. But for every 4 rainy days, there is another 1 day recuperated. Hence, 16-4=12 days extra. Is it me or all the rest of the info is just extraneous?

Actually, your way of thinking is faster. There is only one flaw in your logic. As they worked for 16 days at 50% efficiency, it would have taken extra 16 days to finish job (ONLY IF THEY WORKED AT 50% efficiency). But as they start working at 100% after those 16 days, they are in the deficit of only 16/2 = 8 days. As 4 extra days are provided, the answer is 4. What do you think?

In the first place, I don't know how the company came up with the idea of just needing one day extra if it rained for 4 days.

You see, 80 days = 100% of job

For 4 days, you complete 5% of the job, and that's on a good day. If it rains, you only get 2.5% because of 50% drop in efficiency
Now you have 76 days remaining to complete the job, that translates to 95% of the job
So total job completed = 97.5%. You need to complete another 2.5%. This is equivalent to (2.5/100)*80days = 2 days more (assuming on a good day) and 4 days more (assuming rainy days)

So the company should be allocating 84 days to complete the job (better to consider worst case). But the question says the company expects it to be done in 81 days ? How can that be?