SOLUTION: Cherries cost ​$​4/lb. Grapes cost ​$​2.50/lb. You can spend no more than ​$15 on​ fruit, and you need at least 4lb in all. Create a graph showing the amount of each fr

Algebra ->  Inequalities -> SOLUTION: Cherries cost ​$​4/lb. Grapes cost ​$​2.50/lb. You can spend no more than ​$15 on​ fruit, and you need at least 4lb in all. Create a graph showing the amount of each fr      Log On


   



Question 1198290: Cherries cost ​$​4/lb. Grapes cost ​$​2.50/lb. You can spend no more than ​$15 on​ fruit, and you need at least 4lb in all. Create a graph showing the amount of each fruit you can buy.
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
x pounds of cherries
y pounds of grapes

system%284x%2B2.5y%3E15%2Cx%2By%3E=4%29

2.5y%3E-4x%2B15

y%3E-1.6x%2B6
and
y%3E=-x%2B4


-----below was removed------

Answer by ikleyn(52777) About Me  (Show Source):
You can put this solution on YOUR website!
.
Cherries cost ​$​4/lb. Grapes cost ​$​2.50/lb. You can spend no more than ​$15 on​ fruit,
and you need at least 4lb in all. Create a graph showing the amount of each fruit you can buy.
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            The "solution " presented in the post by @josgarithmetic is incorrect
            starting from the third line of his post to the end.

            I came to bring you a correct solution.


x pounds of cherries
y pounds of grapes


Restrictions

    4x + 2.5y <= 15,
     x +    y >=  4
    x >= 0,  y >= 0.


Plot the lines

    y = -(4/2.5)x + 15/2.5   (red   line in the plot below)
    y =  4 - x               (green line in the plot below)


    graph%28400%2C400%2C-2%2C10%2C-2%2C10%2C+-1.6x%2B6%2C+4-x%29


The solution domain is in the first quadrant below the red line    (including the red line) 
                                         and above the green line  (including the green line).


So, the solutions are the points inside the triangle under the red line, attached to y-axis and above the blue line.


For example, x = 2, y = 2 is the solution (2 pounds of cherries and 2 pounds of grapes).

Solved in a right way, with complete explanations.


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Ignore the post by @jodgarithmetic, for the sake of safety of your mind.