5 painters, each working at the same rate, together can paint a certai

Question

5 painters, each working at the same rate, together can paint a certain fence in 25 days. By what percent must the rate of each painter increase so that they can complete the job in ten days?

A. 125%

B. 150%

C. 200%

D. 250%

E. 275%

GMATinsight · Answer

Manpower is inversely proportional to the time.

So if the time available becomes 10 from 25 (i.e. 2/5 of previous time) the manpower needs to be increased by a factor 5/2

i.e.the increase is (5/2 - 1)*100 = 150%

Answer: option B

pushpitkc · Answer

Another way to solve this problem is to assume the work to be 1250 units.

5 painters paint the fence in 25 days, so each painter would do  10 units of work 
in a day. Since we now have 10 days to complete the work, each of the 5 painters
now has to do  \frac{1250}{5*10}  or  25 units of work

Therefore, the percent increase is  \frac{(25-10)}{10} * 100 = 150 %  (Option B)

warrior1991 · Answer

Initially per day per person work done was 1/125 units(5/x=1/25)
Now per day per person work done will be 1/50 units(5/x=1/10)

Meaning more work needs to be done by every person.

(1/125)*x=1/50
That means x=5/2

Therefore percentage increase = ((5/2-1)/1)*100 =150%

IMO B.

Skyline393 · Answer

5 painters work in 25 days => 1 painter work in 25*5 = 125 days to complete job => Rate of 1 painter = 1/125 => Combined rate of 5 painters = 5/125 = 1/25
If 5 painters complete job in 10 days => Combined rate of 5 painters = 1/10
=> % increase = (new - old)/old * 100 = (1/10 - 1/25)/ (1/25) *100 = 150%. Hence B

sumi747 · Answer

Work done in 25days= 100
Work done each day= 4
Now,
Now new work to be done in 10days= 100
Work done each day would be = 10
Therefore increase in work done per day= {(10-4)/4}*100= 150%
IMO B

Posted from my mobile device

ShahadatHJ · Answer

Total job = 5*25 = 125 units
Hence,  \frac{125}{5} =25
Now,
 \frac{125}{X} =10
X =12.5 (New rate!)
Increase:  \frac{(12.5-5)}{5} *100 = 150%

bumpbot · Answer

Automated notice from GMAT Club BumpBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

5 painters, each working at the same rate, together can paint a certai

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

5 painters, each working at the same rate, together can paint a certai

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards