Working alone, Printers X, Y, and Z can do a certain printing job, in 12, 15, and 18 hours respectively. What is the ratio of the time it takes printer x to do the job tot he time it takes printers Y and Z working together at their individual rates?
4/11
1/2
15/22
22/15
11/4
OG 22/15
The first thing I noticed was that it would take the printer working by himself longer so I eliminated answers 1 2 3. However I dont know how to do the math correctly to pick between the oteher two. I guessed correctly as 11/4 seemed to be too much time difference.
A work Problem
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The time ratio for X:Y:Z = 12:15:18.avada wrote:Working alone, Printers X, Y, and Z can do a certain printing job, in 12, 15, and 18 hours respectively. What is the ratio of the time it takes printer x to do the job tot he time it takes printers Y and Z working together at their individual rates?
4/11
1/2
15/22
22/15
11/4
To make the math easier, divide all of the times by 3:
X:Y:Z = 4:5:6.
Let the job = the LCM of 4, 5, and 6 = 60.
X's rate = w/t = 60/4 = 15 pages per hour.
Y's rate = w/t = 60/5 = 12 pages per hour.
Z's rate = w/t = 60/6 = 10 pages per hour.
Combined rate for Y+Z = 12+10 = 22 pages per hour.
Rate and time are RECIPROCALS.
Since (rate for X alone) : (rate for Y+Z) = 15:22, (time for X alone) : (time for Y+Z) = 22:15.
The correct answer is D.
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Hi Mitch,
My approach is (1/x)/(1/y + 1/z) where x= 12, y=15 and z=18, and the equation yielded the reciprocal of correct answer.
Could you please let me know what is wrong in this approach?
My approach is (1/x)/(1/y + 1/z) where x= 12, y=15 and z=18, and the equation yielded the reciprocal of correct answer.
Could you please let me know what is wrong in this approach?
Regards,
Pranay
Pranay
- anuprajan5
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Pranay,
This is because you are taking the ratios of work rather than that of time.
X can do 1 job in 12 hours. Hence x can do 1/12 job in 1 hour.
When you take a ratio as you as you have done, you are taking the rato of work rather than the ratio of time.
Regards
Anup
This is because you are taking the ratios of work rather than that of time.
X can do 1 job in 12 hours. Hence x can do 1/12 job in 1 hour.
When you take a ratio as you as you have done, you are taking the rato of work rather than the ratio of time.
Regards
Anup