9/10 divided by 3/12
Find the least common multiple
54/60 divided by 15/60
Flip the second fraction and transition from division to multipication
54/60*60/15
Final answer: 3.6 or 3 3/5
It takes 1.5 hours for 4 workers to paint the same room
<em><u>Solution:</u></em>
Given that 3 workers can paint a room in 2 hours
To find: Time taken for 4 workers to paint the same room
Assume the time needed to paint the room is inversely proportional to the number of worker

Where, "k" is the constant of proportionality
<em><u>3 workers can paint a room in 2 hours</u></em>
Substitute number of workers = 3 and time = 2 hours

Therefore,

To find time taken for 4 workers to paint the same room, substitute number of workers = 4 in above expression

Thus it takes 1.5 hours for 4 workers to paint the same room