Elena and Stella can complete a job in 18 hours when they work together if they invite Tommy to help how long will the job take how many friends need to work together to complete the job in 4 hours

Answer 1

IF Elena, Stella and Tommy and other friends all work at the same speed

and 2 working together do the job in 18 hours, then 1 person does the job in 36 hours, 4 will do the job in 9 hours, 8 will do the job in 4.5 hours

You'll need more than 8 to get it done in 4 hours.

9 working together will do the job in 4 hours

people hours done

1 36

2 18 twice as fast as one person

3 12 three times as fast as one person

4 9

5 7.2

6 6

7 36/7 = about 5.14

8 4.5

9 36/9 = 4

16 2.25

36 1

n 36/n

in one hour each will do 1/36 of the job

36 will do the job in 1 hour

36/4 = 9 people will do the job in 4 hours

3 will do 3/36 = 1/12 of the job in 1 hour

3 will do 12/12 of the job= the full job in 12 hours