Question

A machine can complete a job in 6 hours. One day, there was a power failure after 4 hours. find the amount of remaining job.​

Answer 1

Answer:

2 hours will remain for job

Answer 2

Answer:

Machine A takes 6 hours/job, so that's 1/6 jobs/hour.

Machine B takes 4 hours/job, so that's 1/4 jobs/hour.

Now you can add those up, 1/6 + 1/4 jobs/hour working together.

= 5/12 jobs/hour.

Invert that, and you get 12/5 hours/job together, or 2.4 hours.

It looks right, it's less than 4, but more than half of 4. If both machines took 4 hours/job, it's obvious that together it would be half, or 2 hours, but machine B takes 6, so it's gonna be more than 2.

2.4 hours is it.

Step-by-step explanation: