Lobby D.

asked • 12/01/14

System of Equations word problem I can't figure out!!!!

A basketball player scored 40 points in a game. The number of three-point field goals the player made was 22 less than three times the number of free throws (each worth 1 point). Twice the number of two point field goals the player made was 11 more than the number of three point field goals made. Find the number of free-throws, two point field goals, and three point field goals that the player made in the game.


Once I have the equations I understand how to do the problem, but I am obviously doing something wrong because each time I write out the equations I end up getting fractions. 

2 Answers By Expert Tutors

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Bill P. answered • 12/19/14

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A math tutor that is both knowledgeable and patient in secondary math.

Bill P.

The flaw that I notice in other solutions is that the sum of x,y, and z is 40. This is not true. The player did not take 40 shots. Rather he scored 40 points. Each 2-point shot is worth 2 points while each 3-point shot is worth 3 points and each free throw is worth 1 point. so Making "X" free throws (worth 1 point each) "Y" 2-pointers (worth 2-points each) and "Z" 3-pointers (worth 3-points each) implies that the expression to represent the total points scored by this player is not x+y+z, but x + 2y + 3z. Now, set this equal to 40 and create the other equations by carefully reading each statement and translate it into a true math sentence. That is what I did. Then I solved it and checked it.
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12/19/14

Mark M. answered • 12/01/14

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5.0 (278)

Mathematics Teacher - NCLB Highly Qualified

Lobby D.

where did you get the 14 from? Can I show you what I did?
3 pt= x
free throw (1 pt)= y
2 point= z

x+y+z=40
x=3y-22
2z=11+x

so then to put it into ordered equations to use addition/elimination:
x+y+z=40
x-3y=-22
-x+2z=11

yet somehow i keep getting fractions. I don't get it...it seems like exactly what you wrote up there except for the 14 which i am not sure how you got
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12/01/14

Mark M.

The 14 is my error, probably typing and not proofing.
 
All of your equations are correct. I have worked them to z = 12.9!
 
You also?
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12/01/14

Lobby D.

Yeah I knew that was wrong because it's a multiple choice problem and all the answers were whole numbers. I finally figured it out, it was because we were not accounting for the fact that some were worth 3 points and 2 points.
so then system should have been:
3x+y+2z=40
x-3y=-22
-x+2z=11
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12/01/14

Mark M.

Lobby,
 
Thank you. I can sleep tonight!
 
Mark
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12/01/14

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