SOLUTION: Five workers install a pipe in 15 hours. How long will it take 9 workers to install the same pipe at the same rate?

Five workers install a pipe in 15 hours. How long will it 
take 9 workers to install the same pipe at the same rate?

Since five workers install a pipe in 15 hours,
it would take 1 worker 5 times as long or 75 hours

So it would take 9 workers th as long as THAT.

th of 75 is  or  or  hours or
8 hours and 20 minutes.

Second way:

Use the worker-time-job formula, which is:



where

W1 = the number of workers in the first situation.
T1 = the number of time units (hours in this case) in the first situation.
J1 = the number of jobs in the first situation.

W2 = the number of workers in the second situation.
T2 = the number of time units (hours in this case) in the second situation.
J2 = the number of jobs in the second situation.

W1 =  5             W2 = 9      
T1 = 15             T2 = the unknown quantity 
J1 =  1             J2 = 1







 







8 hours and 20 minutes.

Edwin