document.write( "Question 269374: A farmer spends $4,000 to obtain 100 head of livestock.Prices are: calves – $120 each; lambs – $50 each; piglets – $25 each. If he purchased at least one animal of each type and fewer than 10 calves, how many lambs did he buy?\r
\n" ); document.write( "\n" ); document.write( "(1) 44 (2) 46 (3) 48 (4) 50 (5) None of the above
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Algebra.Com's Answer #197526 by ptaylor(2198)\"\" \"About 
You can put this solution on YOUR website!
Let x=number of calves
\n" ); document.write( "Let y=number of lambs
\n" ); document.write( "And let z=number of piglets
\n" ); document.write( "Now we are told that:
\n" ); document.write( "x+y+z=100---------------------eq1
\n" ); document.write( "120x+50y+25z=4000
\n" ); document.write( "Divide each term by 5 just to deal in smaller numbers
\n" ); document.write( "24x+10y+5z=800----------eq2
\n" ); document.write( "We have only two equations but three unknowns. Hmmmmmmm.
\n" ); document.write( "BUT WE CAN STILL SOLVE IT!!\r
\n" ); document.write( "\n" ); document.write( "Multiply eq1 by 5 and then subtract it from eq2 and we get:
\n" ); document.write( "19x+5y=300----------eq1a
\n" ); document.write( "solve for y
\n" ); document.write( "y=(300-19x)/5---eq1b Now we have an equation that relates the number of lambs to the number of calves
\n" ); document.write( "We know several things about this problem that will help us solve it:
\n" ); document.write( "(1) We are told that the number of calves,(x),is less than 10
\n" ); document.write( "(2) We know that we can't have a half a calf, a leg of lamb or a piece of pork. We must deal in whole numbers.
\n" ); document.write( "(3) We can't have negative calves, lambs or piglets. We must deal in whole, positive numbers.
\n" ); document.write( "We will now solve eq1b by trial and error, starting with x=9.
\n" ); document.write( "x=9 y=(300-171)/5--------------no good not a whole number
\n" ); document.write( "x=8 y=(300-152)/5--------------no good not a whole number
\n" ); document.write( "x=7 y=(300-133)/5--------------no good not a whole number
\n" ); document.write( "x=6 y=(300-114)/5--------------ditto
\n" ); document.write( "x=5--------y=(300--95)/5=41-----------BINGO ---POSSIBLE SOLUTION
\n" ); document.write( "BY INSPECTION WE CAN SEE THAT WHEN x IS 4, 3, 2 OR 1. WE DO NOT GET ANY MORE WHOLE NUMBERS FOR Y
\n" ); document.write( "Now we have the following:
\n" ); document.write( "x=Calves=5
\n" ); document.write( "y=Lambs=41 ----so your answer is \"none of the above\"
\n" ); document.write( "Substitute these values into eq1 and we get
\n" ); document.write( "5+41+z=100
\n" ); document.write( "z=Piglets=54
\n" ); document.write( "Now
\n" ); document.write( "5*120+41*50+54*25=4000
\n" ); document.write( "600+2050+1350
\n" ); document.write( "4000=4000\r
\n" ); document.write( "\n" ); document.write( "Hope this helps---ptaylor\r
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