Question

4 people can paint 6 wall is 30 minutes.
How many minutes will it take 7 people to paint 9 walls???

Answer 1

Try to understand the concept from here.
http://openstudy.com/users/siddhantsharan#/updates/4f5a2f42e4b0636d8905cb79

Answer 2

4 ppl ----6 walls ----30 mins.
1 per-----6/4 wall ---30mins
1 per------1wall ---30*4/6 mins
7ppl ----9 walls
1 pr needs----- 9/7walls
Thereore time = 9/7*30*4/6
25.7 mins

Answer 3

I think of it as people*time = work and you need a certain amount of work to finish a job.
so as a ration
\[ \frac{4*30}{6}=\frac{7t}{9} \]
now solve for t by multiplying both sides by 9/7

Answer 4

*ratio