SOLUTION: Mary's favorite cookie recipe makes 3 dozen cookies. For the class party, she needs 5 dozen cookies. She is concerned that she may not have enough flour to bake them without a trip

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: Mary's favorite cookie recipe makes 3 dozen cookies. For the class party, she needs 5 dozen cookies. She is concerned that she may not have enough flour to bake them without a trip      Log On


   



Question 135878: Mary's favorite cookie recipe makes 3 dozen cookies. For the class party, she needs 5 dozen cookies. She is concerned that she may not have enough flour to bake them without a trip to the grocery. If the recipe uses 2 1/2 cups of flour to make 3 dozen cookies, how much flour will be needed to make 5 dozen cookies?
Answer by ptaylor(2198) About Me  (Show Source):
You can put this solution on YOUR website!
Let x=amount of flour needed for 5 doz cookies
2 1/2 cups of flour is to 3 doz cookies as x cups of flour is to 5 doz cookies and this is written as follows
(2 1/2)/3=x/5 cross multiply ( or multiply each side by 15)

5*(2 1/2)=3x or
12 1/2=3x and this equals
25/2=3x divide both sides by 3
x=25/6=4 1/6 cups--- amount of flour needed for 5 doz cookies
or we could look at it this way:
2 1/2 cups--------------- 3 doz
5 cups------------------------6 doz
5/6 cups---------------------1 doz
5*(5/6)------------------------5 doz or
4 1/6 cups----------------------5 doz

Hope this helps---ptaylor