dimri10 wrote:
One robot builds a robot in 1 hour, another one builds a robot in 2 hours. The 2 robots work together and when a new robot is complete, it joins the others, working at a constant rate of one robot in 2 hours. How much time will it take until there are 5 robots altogether, if the robots build only one robot at a time?
A. 70 min
B. 94 min
C. 110 min
D. 112 min
E. 120 min
The rate of the first robot is 1 and the rate of the second robot is 1/2. Thus it will take both of them 1/(1 + 1/2) = 1/(3/2)
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