Unit 7 · Finding Procedures
Two Workers, One Factory — How Long Together?
Lesson 3 of 4
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About this lesson
Combined-work questions use rates, not averages: each worker completes 1÷time of the job per day — add the rates, then take the reciprocal for total time.
Chapters
0:00Introduction
0:21The Question
0:58Worker A: Individual Daily Production Rate
1:23Worker B: Individual Daily Production Rate
1:46Calculating the Combined Daily Rate
2:04Solving for Total Collaborative Days
2:32Exam Strategy — The Product Over Sum Formula
3:22Confirming the Final Option
Question
A factory has a task to produce 3600 parts. If it is given to Worker A only, it will take 30 days. If it is given to Worker B only, it will take 20 days. Now they are working together. In how many days can they finish the task?
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