Sisters HW (test) help
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chris is the devil
Joined: Nov 2002
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From: so cal 951 + 760
Sisters HW (test) help
8)
A rug is made by weaving 20lbs of yarn that is 50% wool with a yarn that is 25% wool. How many pounds of the 25% wool must be used if the finished rug is to be 35% wool?
thanks
Sean
A rug is made by weaving 20lbs of yarn that is 50% wool with a yarn that is 25% wool. How many pounds of the 25% wool must be used if the finished rug is to be 35% wool?
thanks
Sean
Push to shock!
Joined: Sep 2002
Posts: 4,583
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From: Palo Alto, CA
It's a weighted average
x = number of lbs of 35% yarn needed
20 lbs of yarn*0.5 wool + x lbs of yarn*0.35 wool = number of pounds of wool in rug
20 + x = total weight of rug
You want (number of pounds of wool in rug)/ (total weight of rug) = 0.35
So if you solve this you get 30 lbs
x = number of lbs of 35% yarn needed
20 lbs of yarn*0.5 wool + x lbs of yarn*0.35 wool = number of pounds of wool in rug
20 + x = total weight of rug
You want (number of pounds of wool in rug)/ (total weight of rug) = 0.35
So if you solve this you get 30 lbs
Joined: Jul 2003
Posts: 28,282
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From: michigan
Originally Posted by Kestrel
It's a weighted average
x = number of lbs of 35% yarn needed
20 lbs of yarn*0.5 wool + x lbs of yarn*0.35 wool = number of pounds of wool in rug
20 + x = total weight of rug
You want (number of pounds of wool in rug)/ (total weight of rug) = 0.35
So if you solve this you get 30 lbs
x = number of lbs of 35% yarn needed
20 lbs of yarn*0.5 wool + x lbs of yarn*0.35 wool = number of pounds of wool in rug
20 + x = total weight of rug
You want (number of pounds of wool in rug)/ (total weight of rug) = 0.35
So if you solve this you get 30 lbs
