A Time-Rate ProblemDate: 8/14/96 at 10:32:18 From: Anonymous Subject: A Time-Rate Problem A can finish a project in 1.5 years, B in 1 year, and C in 9 months; how long does it take to finish if A, B, and C work together? Thanks, Sg Date: 8/30/96 at 17:14:19 From: Doctor Jerry Subject: A Time-Rate Problem The key to problems like this is to notice how much of the project can be done by each of A, B, and C in a common time period. If A can finish in 1.5 (=3/2) years, then A can do 2/3 of the project in 1 year. If B can finish in 1 year, then B can do 1/1 of the project in 1 year. If C can finish in 9 months (3/4 year), then C can do 4/3 of the project in 1 year. Working together, they can do 2/3 + 1/1 +4/3 = 3 projects in 1 year. So, they can finish 1 project in 1/3 of a year. -Doctor Jerry, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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