Can someone show me where I"m going wrong?

A = 1/12 of the work in 1 day working 2 shifts

B = 1/15 of the work in 1 day working 2 shifts

If you cut the # of shifts to 1 each, that's cutting the rate in half, so you'd only get 1/2 the work done in 1 day for 1 shift

A = 1/24 of the work in 1 day on 1 shift

B = 1/30 of the work in 1 day on 1 shift.

Together, they get \(\frac{1}{24} + \frac{1}{30}\) of the work done in 2 shifts.

1/24 + 1/30...find a common factor...120. So 1/24 = ?/120 = 5/120 and 1/30 = ?/120 = 4/120 so 9/120 in 2 shifts...but they each get another 1/2 shift. so half of 9/120 is 4.5/120 (yes, I know it's not good to use decimals, but it will make sense the ease of use in a second). so 13.5/120 is the same as 17/240. This should be the amount of work the machines can do together in 1.5 shifts each per day.

now 240/17 gives us just over 14, meaning it won't quite finish all of the work in 14 days, but that's the closest we have for an answer.

I answer A, but am not 100% sure about it.

bigfernhead wrote:

Two machines are sawing wood but due to space limitations only one at a time can operate. Machine A is used for the first shift and the other machine for the second shift, while both work half of the third shift. Machine A can do the job in 12 days if it worked two shifts and Machine B can do the job in 15 days if it worked two shifts. How many days will it take to do the job with current work schedule?

14

13

11

9

7

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J Allen Morris

**I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a$$.

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