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jxharmon

Member

Registered: 2007-01-08

Posts: 104

Double check on word problem..plz

coffee beans sell for $9 per pd and $12 pe4r pd; the 2 are mixed to create 100 pds that sell for $11.25 per pd;
how much of each type will be used?

x(beans sold @$9 pd) + y(beans sold @$12 pd)=100
9(12y+100)+12y=1125
108y+900+12y=1125
120y+900=1125
120y=1125-900
120y=225
What am I missing???
x=25 pds, y=75 pds

pi man

Member

Registered: 2006-07-06

Posts: 251

Re: Double check on word problem..plz

x+y = 100          x is the $9 coffee, Y is the 12.

9x + 12y = $11.25 (100)
9x+12y = 1125

now substitue 100-y for x
9(100-y) + 12y = 1125
900 - 9y + 12y = 1125
3y = 225
y =75

And x = 100-y=25

Doublecheck: $9/pound (25 pounds) + $12/pound (75pounds)= $225 + $900 = $1125

John E. Franklin

Member

Registered: 2005-08-29

Posts: 3,588

Re: Double check on word problem..plz

#A:  (9x + 12y) ÷ (x + y) = 11.25, I think.
#B:  x + y = 100 lbs.
#B2: x = 100 - y
#A3: (9x + 12y) = 1125.
#A4: 9(100 -  y) + 12y = 1125.
#A5: 900 - 9y + 12y = 1125.
#A6: 3y = 1125 - 900
#A7: y = 225 / 3, which is 75.
Plug 75 into #B2 for x=25 pds (or "lbs." in USA)

(edit-append) Ooops!! pi man already did it?!!?  Oh well, can't hurt I guess.

Last edited by John E. Franklin (2007-02-06 16:27:43)

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