These are sample practice MCQs created for exam preparation. These are NOT official exam questions.
Machine A can complete a job in 6 hours, and Machine B can complete the same job in 4 hours. Working together, how long will it take them to complete the job?
Question:
Machine A can complete a job in 6 hours, and Machine B can complete the same job in 4 hours. Working together, how long will it take them to complete the job?
Machine A can complete a job in 6 hours, and Machine B can complete the same job in 4 hours. Working together, how long will it take them to complete the job?
Options
Answer: (B) 2.4 hours
Explanation:
Rate of A = 1/6 jobs/hour. Rate of B = 1/4 jobs/hour. Combined rate = 1/6 + 1/4 = 2/12 + 3/12 = 5/12 jobs/hour. Time = 1 job ÷ (5/12 jobs/hour) = 12/5 = 2.4 hours.
Explanation:
Rate of A = 1/6 jobs/hour. Rate of B = 1/4 jobs/hour. Combined rate = 1/6 + 1/4 = 2/12 + 3/12 = 5/12 jobs/hour. Time = 1 job ÷ (5/12 jobs/hour) = 12/5 = 2.4 hours.
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