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A dessert recipe calls for 50% melted chocolate and 50% rasp

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Re: A dessert recipe calls for 50% melted chocolate and 50% rasp [#permalink]

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New post 07 Jan 2016, 07:03
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vaishnogmat wrote:
A dessert recipe calls for 50% melted chocolate and 50% raspberry puree to make a particular sauce. A chef accidentally makes 15 cups of the sauce with 40% melted chocolate and 60% raspberry puree instead. How many cups of the sauce does he need to remove and replace with pure melted chocolate to make the sauce the proper 50% of each?

A. 1.5
B. 2.5
C. 3
D. 4.5
E. 5


Hi all,
another approach to this Q, which could be slightly easier and less time consuming is..
15 cups with 40% of choc will mean there are 6 cups of choc..
what was it supposed to be.. 50% or .5*15=7.5 cups..
this is 1.5 cups short..

now he is to make up for this 1.5 cups..
if we take out one cup, which includes .4 choc and add one cup of pure choc, the final effect is addn of .6 cup of choc..

But we have to make up for 1.5 cups..
if .6 cup requires replacement of one cup,..
1.5 cup will require 1/.6 *1.5= 2.5 cups..
ans B
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Re: A dessert recipe calls for 50% melted chocolate and 50% rasp [#permalink]

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New post 20 May 2016, 11:19
Can someone please explain if the quantity of Raspberry in the original (faulty) and the final mixture will remain the same? Since we are only adding Chocolate?
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Re: A dessert recipe calls for 50% melted chocolate and 50% rasp [#permalink]

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New post 21 May 2016, 00:31
powellmittra wrote:
Can someone please explain if the quantity of Raspberry in the original (faulty) and the final mixture will remain the same? Since we are only adding Chocolate?


No. He is going to remove the sauce (mix of chocolate and raspberry) and then add more chocolate to it. So the initial amount of raspberry is not the same as the final amount. But after the removal process, he adds only chocolate so yes, in that step, the amount of raspberry does not change.

Check here for the complete solution: a-dessert-recipe-calls-for-50-melted-chocolate-and-50-rasp-158248.html#p1376400
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Re: A dessert recipe calls for 50% melted chocolate and 50% rasp [#permalink]

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New post 21 May 2016, 11:57
let x=number of cups to be removed/replaced
15(.4)-x(.4)+x=15(.5)
x=2.5 cups
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Re: A dessert recipe calls for 50% melted chocolate and 50% rasp [#permalink]

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New post 22 May 2016, 22:15
Responding to a pm:

Quote:
Why does it have to be 50 = 60[(15-x)/15] ?

i.e the initial Volume is 15 not 15-x?


We assume that he removes x cups.

Our formula is based on the concept that amount of raspberry puree does not change in the step.
Initial amount = Final amount
CiVi = CfVf

Think about it: when does the amount of raspberry puree remain same?
When you have 15 cups of mix, there is a certain amount of raspberry puree in it. When you remove x cups, the amount of raspberry puree reduces. You have 15 - x cups of mix now. Now when you add chocolate, the amount of raspberry puree stays the same. So we are applying the concept of "amount stays same" to the "adding chocolate" step only. Before we add chocolate, we have 15-x cups of mix. After we add chocolate, we have 15 cups of mix. Hence, initial volume is 15 - x. Does this help?
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Re: A dessert recipe calls for 50% melted chocolate and 50% rasp [#permalink]

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New post 17 May 2017, 17:57
1
vaishnogmat wrote:
A dessert recipe calls for 50% melted chocolate and 50% raspberry puree to make a particular sauce. A chef accidentally makes 15 cups of the sauce with 40% melted chocolate and 60% raspberry puree instead. How many cups of the sauce does he need to remove and replace with pure melted chocolate to make the sauce the proper 50% of each?

A. 1.5
B. 2.5
C. 3
D. 4.5
E. 5


We've got 9 cups of raspberry and 6 of chocolate. To fix this, we need to remove 1.5 cups of raspberry.

But! We can't take out raspberry by itself. It's already mixed with the chocolate. We can only remove the mix.

Mix = 60% raspberry, 40% chocolate

Every cup of mix we remove = 0.6 cups raspberry + 0.4 cups chocolate

60% of 1 cup = 0.6 cups

So each cup of mix gets us 0.6 cups raspberry

0.6 cups of raspberry * (# of cups of mix) = 1.5 cups of raspberry

0.6 * x = 1.5

x = 2.5

We need 1.5 cups raspberry 0.6 * 2.5 = 1.5

So we need to remove 2.5 cups of mix.

Answer : B
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Re: A dessert recipe calls for 50% melted chocolate and 50% rasp [#permalink]

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New post 22 May 2017, 18:40
vaishnogmat wrote:
A dessert recipe calls for 50% melted chocolate and 50% raspberry puree to make a particular sauce. A chef accidentally makes 15 cups of the sauce with 40% melted chocolate and 60% raspberry puree instead. How many cups of the sauce does he need to remove and replace with pure melted chocolate to make the sauce the proper 50% of each?

A. 1.5
B. 2.5
C. 3
D. 4.5
E. 5


We are given that a chef makes 15 cups of sauce with 40% melted chocolate, or 15 x 0.4 = 6 cups of melted chocolate, and 60% raspberry puree, or 0.6 x 15 = 9 cups of raspberry puree. We need to determine how many cups of the sauce he needs to remove and replace with pure melted chocolate to make the sauce 50% of each. In order to have 50% of each, we want 7.5 cups of melted chocolate and 7.5 cups of raspberry puree. We can let n = the number of cups of sauce removed and also the number of cups of pure melted chocolate added.

Recall that we have 6 cups of melted chocolate in the sauce (which is 40% of the sauce). If we remove n cups of sauce, we are actually removing 0.4n cups of melted chocolate. Since we are adding back n cups of pure melted chocolate, the number of cups of melted chocolate will increased by n, and we want the end result to be 7.5 cups of melted chocolate. Thus, we can create the following equation to solve for n:

6 - 0.4n + n = 7.5

0.6n = 1.5

n = 1.5/0.6 = 15/6 = 2.5

Answer: B
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Re: A dessert recipe calls for 50% melted chocolate and 50% rasp [#permalink]

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New post 12 Jan 2018, 13:36
Hi All,

This question can be solved by TESTing THE ANSWERS.

To start, we're told that 15 cups of 'sauce' are made up of 40% chocolate and 60% raspberry. This gives us...

Total = 15 cups
Choc = 40%(15) = 6 cups
Rasp = 60%(15) = 9 cups

We're told to remove a certain amount of the mixture and replace it with PURE chocolate, so that the mixture becomes a 50/50 chocolate/raspberry mix. In simple terms, we need the total amount of Chocolate to be 7.5 CUPS. We're asked for the number of cups of the mixture that would have to be replaced. Let's TEST THE ANSWERS.

While it's mathematically advantageous to TEST answer B or D first, Answer C seems like easier math...

IF... we remove 3 cups of sauce, those 3 cups are....
40%(3) = 1.2 cups Choc
60%(3) = 1.8 cups Rasp

The number of cups of Choc can be calculated by using the original number of cups (6), subtracting the amount removed when we remove the sauce (in this case, 1.2), then adding back the pure chocolate that replaces the removed sauce (in this case, 3) = 6 - 1.2 + 3 = 7.8 cups chocolate. This is TOO MUCH chocolate (we wanted it to be 7.5 cups), but it's fairly close, so we're likely looking for an answer that is CLOSE to 3....Let's TEST Answer B...

IF... we remove 2.5 cups of sauce, those 2.5 cups are....
40%(2.5) = 1 cup Choc
60%(2.5) = 1.5 cups Rasp

Choc = 6 - 1 + 2.5 = 7.5 cups chocolate. This is EXACTLY what we're looking for, so this MUST be the answer.

Final Answer:

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Re: A dessert recipe calls for 50% melted chocolate and 50% rasp   [#permalink] 12 Jan 2018, 13:36

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