posted by Lisa on .
The officejet printer can copy sues dissertation in 16 minutes. The laser printer can copy the same document in 22 minutes. If the two machines work together, how long would they take to copy the dissertation?
rate of first copier = job/16
rate of 2nd copier = job/22
combined rate = job/16 + job/22 = job(19/176)
time at combined rate = job/(19job/176) = 176/19
or 9.26 minutes.