Question

A local dairy has three machines to fill half-gallon milk cartons. The machines can fill in the dialy quota in 6 hours, 7 hours, and 5.25 hours, respectively. Find how long it takes to fill the daily quota if all three machines are running.
It takes _ hours to fill the daily quota if all three machines are running.

Please show me how to do this, and I will give a medal.

I think the beginning equation is: 1/6+1/7+1/5.25=1/x. My answer is 0.50 hours, nut I just want to be sure. Thank you!

Answer 1

1/x = 1/2 That's what you got with your equation. So far so good. That does not tell you what x is though. You have go just a bit further.

1/x = 1/2 Cross multiply

x = 1 * 2

x = 2 It takes 2 hours to complete with all three machines working.