Uncle Bruce is baking chocolate chip cookies. He has 36 ounces of doug

Hi,
IMO is should be B
reason: Total new formed cookie contains 80% of dough only.
80% of 100 = 36
total cookie is of 45 ounce
20% of 45 is 9 ounce of chocolate.
hence 15-9 = 6 ounce of chocolate is left.

Regards
Celestial


Kudos,if the solution is correct.

Let total weight of cookies = x

dough used = 36 ounces, which is 80% of the total

=> \(\frac{80}{100} *x = 36\) => x= 45 ounces

Out of 45 ounces, 20% is chocolate => \(\frac{20}{100}*45\) = 9 ounces

Thus, leftover chocolate = 15 - 9 = 6 ounces.

Hence, answer is B

My answer choice is B, took me a little too long, but here is my process:

First I recognize that the answer choices indicate the exact amount of chocolate used by subtracting them from 15 ounces, so

A) 15-3left over = 12 ounces used 12+36= 48 --->48/12 gives 4, so 1/4 of the mixture is choc AKA 25%: too much!
B) 15-6left over= 9 ounces choc used 9+36 = 45 ---> 45/9 gives 5, so 1/5 of the mixture is choc AKA 20 % and this is the answer

The ratio of chocolate : dough in the cookies is \(=\,20\%\,:\,80\%\) \(\,=\,1\,:\,4\)

Since uncle Bruce is using all of \(36\) ounces of dough, then the ratio of chocolate : dough is \(=\,9\,:36\,\)

So, the chocolate left unused is \(15\,-\,9\,=\,6\) ounces

Answer B

Dough/Chocolate = 80/20 = 4/1 => 4 parts = 36 => 1 part = 9
Therefore 15-9 = 6 remaining , answer is A

Hi gamerssc,

Your thinking in regards to this question is spot-on, but you still have to make sure that you're bubbling the correct answer on Test Day.

GMAT assassins aren't born, they're made,
Rich

VERITAS PREP OFFICIAL SOLUTION:

Now, we don’t want to gloss over the math here but there’s plenty of opportunity to practice with word problems and ratios in other posts and resources, so let’s cut to the true takeaway here. Most students will correctly arrive at the amount of chocolate used by employing a method similar to:

If the 36 ounces of dough are to be 80% of the total weight, then 36 = 4/5 * total.

That means that the total weight is 45 ounces, and so when we subtract out the 36 ounces of dough, there’s 9 ounces of chocolate in the cookies.

So…the answer is E. Right?

Wrong. Go back and double-check the question – the question asks for how much chocolate is LEFT OVER, not how much is USED. To be correct, you’d need to go back to the 15 original ounces of chocolate, subtract the 9 used, and correctly answer that 6 were left.

What’s the trap? GMAT questions are frequently set up so that you can answer the wrong question. If a question asks you to solve for y, it typically makes it easier to first solve for x…and then x is a trap answer. If a question asks you to strengthen a conclusion, the best way to weaken it is likely to be an answer choice. If a question asks for the maximum value, the minimum is going to be a trap.

The most common wrong answer to any problem on the GMAT is the right answer to the wrong question.

So take precaution – to avoid this trap, make sure that you:

Circle the variable for which you’re solving, or write down the question at the top of your work.

Jot a question mark at the top of your noteboard on test day, and tap it with your pen before you submit your answer to double check “did I answer the right question?”

Keep track of your units in word problems (minutes vs. seconds, amount used vs. amount remaining) and double check the units of your answer against the question
Make note of every time you make that mistake in practice, and as a more general tip be sure not to write off silly mistakes as just “silly mistakes”. If you made them in practice, you’re susceptible to them on the test, so make a note to watch out for them particularly if you’ve made the same mistake twice.
Few outcomes are more disappointing than doing all the work correctly but still getting the question wrong. The GMAT doesn’t do partial credit, so on a question like this falling for the trap is just as bad as not knowing how to get started. Get credit for what you know how to do – make sure you pause before you submit your answer to make sure that it answers the proper question!

The cookies contain 20% chocolate and 80% dough.

Since all the dough is consumed, therefore 80% of total cookie mixture = 36 ounces

Therefore, Total mixture = 36*100/80 = 45 ounces.

Chocolate used = 45 - 36 = 9 ounces.

Left-over chocolate = 15 - 9 = 6 ounces

Ans- B

Answer is B.

x/x+36=1/5
x=9

15-9=6

20% chocolate means 80% must be donuts

i.e. 36 ounces = 80% of total Weight
i.e. 20% of total Weight = (36/80)*20 = 9 ounces

i.e. Chocolates Left-over = 15 - 9 = 6 Ounces

Answer: option B

Solution : Let d and c be amounts of dough and chocolate used.
0.2(d+c)=c ==> c= d/4=9
Remaining = 15-9 = 6

Option B

We have 36 ounces of dough and 15 ounces of chocolate.

We know the cookies consist of 20% chocolate.

so we are adding two weights, obviously the whole weight of the cookies is more: say x

so 80/100= 4/5 of x = 36

x = 45

amount of chocolate used = 45-36 = 9

15-9 = 6 ounces left

OA: B

cookies contain 20 % chocolates and 80% dough.
So, the ratio of chocolate to dough is 1:4
Let the amount of chocolate use be x.
Then,
\(\frac{x}{36}\)=\(\frac{1}{4}\)
or x= 9

So, the amount of chocolate left is
15-9 = 6 ounces

Answer:- B

Hi All,

This question can be solved in a couple of different ways. Here's an algebraic approach:

We're told to use 36 ounces of dough and enough chocolate (I'll refer to this amount as X ounces) so that the cookies are 20% CHOCOLATE. This is ultimately a ratio; the information can written in a couple of ways. Here's one...

Chocolate/All = X/(36+X) = 1/5

Now we can solve for X...

5X = 36 + X
4X = 36
X = 9

Thus, 9 ounces of chocolate are needed. Since we started with 15 ounces of chocolate, and the question asks how many ounces are LEFT OVER...

15 - 9 = 6 ounces left over.

Final Answer:

GMAT assassins aren't born, they're made,
Rich

We need to find the dough to chocolate ratio to calculate how much chocolate will be used or will remain.

Let \(C\) represent the chocolate and \(D\) represent the dough in the cookies.
Uncle Bruce wants to have only 20% chocolate in the cookies which means that \(C/(C+D)\)=\(20%\) or \(1/5\)
Solving this equation we get:
\(5C=C+D\)
\(4C=D\). This gives us the dough to chocolate ratio of \(1/4\)

Now, if all the dough (36 ounces) is used then:
\(4C=36\)
\(C=9\). Hence, if 9 ounces of chocolate is used then \(15-9 = 6\) ounces of chocolate remain.
Ans. Option B

Let x = the amount of chocolate to be used so that the cookies consist of 20% chocolate. We have:

x/(36 + x) = 20/100

x/(36 + x) = 1/5

5x = 36 + x

4x = 36

x = 9

Thus, if the cookies are to contain 20% chocolate, 15 - 9 = 6 ounces of chocolate will remain.

Answer: B

Hi all ,

Why can’t we say that 1/5 of total cookies is contains chocolate and frame the equation like :
1/5 of total =15 ; so total is 75 !!! I am confused

Plz help

Posted from my mobile device