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 By: brightstars (offline)  Sunday, August 14 2011 @ 11:06 AM CDT (Read 2566 times)
brightstars

Hi

Just chanced upon this wonderful website!

Machine A and B each printed a fixed number of newspapers per hour.
Machine B started printing earlier at a rate of 75 copies per hour.
After Machine B had printed for 10 hours, Machine A had printed 340 copies.
After Machine B had printed 16 hours, Machine A had printed 886 copies.

a. How many copies of newspapers did Machine A print per hour?

b. How long would Machine B have worked when both machines have printed a total of 2750 copies?

Ans: a. 91 copies per hour
b. 20 hours

Thank you!!

Newbie

Registered: 08/11/11
Posts: 2

 By: KJPang (offline)  Sunday, August 14 2011 @ 10:49 PM CDT
KJPang

Hi,

Below are my workings, hope its helpful.

MA: Machine A
MB: Machine B

(a) MA: at the 10th hour, MA printed 340 copies.
at the 16th hour, MA printed 886 copies
so, within 6 hours, MA printed 886-340=546 copies
546 / 6 = 91 copies

Ans: MA printed 91 copies per hour.

(b) If both MA and MB work together, they can print 75+91=166 per hour.

At the 16th hour, MA and MB printed a total of (16x75) + 886 = 2086 copies

2750 - 2086 = 664
664 / 166 = 4 hours

4 hours + 16 hours = 20 hours

Ans: 20 hours.

Newbie

Registered: 04/21/11
Posts: 6

 By: brightstars (offline)  Monday, August 15 2011 @ 10:20 PM CDT
brightstars

Hi JKPang,

Newbie

Registered: 08/11/11
Posts: 2

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