Question 1162966
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A variation on the alternative mental solution provided by tutor @ikleyn....<br>
Since the newer computer works twice as fast as the older, when doing the job together in 25 minutes the newer computer does 2/3 of the job.<br>
If it takes the newer computer 25 minutes to do 2/3 of the job, it will take it (3/2)*25 = 37.5 minutes to do the whole job.<br>
ANSWER: 37 1/2 minutes<br>