SOLUTION: I am working on these types of word problems and I just don't understand how to set it up my word problem is: the cost of nails varies directly with the number of pounds bought. If

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: I am working on these types of word problems and I just don't understand how to set it up my word problem is: the cost of nails varies directly with the number of pounds bought. If      Log On


   

Question 996001: I am working on these types of word problems and I just don't understand how to set it up my word problem is: the cost of nails varies directly with the number of pounds bought. If 4 pounds of nails cost 11.60, what is the cost of 3.5 pounds? If I could just see an example of how to set a problem like this up it would be greatly appreciated

Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
.
X=cost of 3.5 lbs
.
Set up as a ratio:
11.60%2F%284lbs%29=X%2F%283.5lbs%29
.
Look at what is happening: The left side is
calculating the price per pound, so when we multiply
by 3.5lbs, we are multiplying cost per pound by pounds:
.
%283.5lbs%29%2811.60%2F%284lbs%29%29=X
.
%283.5lbs%29%282.90%2Flb%29=X (Notice the price per pound is 2.90)
10.15=X
.
ANSWER: The price of 3.5 pounds is 10.15.