MATH-UA 120 Lecture Notes - Lecture 10: Jet Stream, Street Sweeper
Document Summary
Crane a can unload the container ship in 10h, and crane b can unload it in 14h. Let t= the number of hours cranes a worked. Let t-2 = the number of hours crane b worked. Thus, the part of the job crane a can do in t hours is t/10. Crane b"s rate is 1/14 so the work done is (t-2)/14. Since the two are working together so we add t/10 and (t-2)/14 = 1 (one because it is one whole job) T= 80/12 or 6 hours 2/3 minutes. Now we add 6 hours 2/3 minutes to noon and the answer is 6:40 p. m. A town"s old street sweeper can clean the streets in 60 hours. The old sweeper together with a new sweeper can clean the streets in 15 hours. Old sweeper can do the job at a rate of 1/60 in one hour.
