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Miguel is mixing up a salad dressing. Regardless of the [#permalink]
20 Feb 2011, 11:44

1

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A

B

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E

Difficulty:

35% (medium)

Question Stats:

63% (02:56) correct
36% (02:09) wrong based on 246 sessions

Miguel is mixing up a salad dressing. Regardless of the number of servings, the recipe requires that 5/8 of the finished dressing mix be olive oil, 1/4 vinegar, and the remainder an even mixture of salt, pepper and sugar. If Miguel accidentally doubles the vinegar and forgets the sugar altogether, what proportion of the botched dressing will be olive oil?

Re: PS - Salad Dressing Mix Problem [#permalink]
20 Feb 2011, 11:57

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Expert's post

noodlesalad wrote:

Hi guys, can you have a go at this question? I'm not getting the one of the available answers.

Miguel is mixing up a salad dressing. Regardless of the number of servings, the recipe requires that 5/8 of the finished dressing mix be olive oil, 1/4 vinegar, and the remainder an even mixture of salt, pepper and sugar. If Miguel accidentally doubles the vinegar and forgets the sugar altogether, what proportion of the botched dressing will be olive oil?

a) 15/29 b) 5/8 c) 5/16 d) 1/2 e) 13/27

Olive oil = 5/8 = 15/24 --> 15 parts out of 24; Vinegar = 1/4 = 6/24 --> 6 parts out of 24; Salt + pepper + sugar = 1-(15/24+6/24)= 3/24, so each = 1/24 --> 1 part out of 24 each;

If vinegar = 12 (instead of 6) and sugar = 0 (instead of 1) then total = 15+12+1+1+0 = 29 parts out of which 15 parts are olive oil --> proportion = 15/29.

Answer: A.

P.S. Took 24 as common denominator so that share of each ingredient to be integer.

Re: PS - Salad Dressing Mix Problem [#permalink]
20 Feb 2011, 12:01

noodlesalad wrote:

Hi guys, can you have a go at this question? I'm not getting the one of the available answers.

Miguel is mixing up a salad dressing. Regardless of the number of servings, the recipe requires that 5/8 of the finished dressing mix be olive oil, 1/4 vinegar, and the remainder an even mixture of salt, pepper and sugar. If Miguel accidentally doubles the vinegar and forgets the sugar altogether, what proportion of the botched dressing will be olive oil?

a) 15/29 b) 5/8 c) 5/16 d) 1/2 e) 13/27

Since this is a pure ratio problem, I'd probably find it easiest just to choose a convenient number for the amount of salad dressing we're making. You could also work purely with fractions, though that's a bit more awkward. Here, we know that 5/8 of the dressing is oil, 2/8 is vinegar, and the remaining 1/8 is an equal mixture ('even'? they mean 'equal') of salt, pepper and sugar, so (1/3)(1/8) = 1/24 of the dressing is salt, 1/24 is sugar, and 1/24 is pepper. So we can suppose we would normally be making 24 units of the dressing. We then normally would have:

15 units of oil 6 units of vinegar 1 unit of sugar 1 unit of salt 1 unit of pepper

Now if we double the vinegar and omit the sugar we have

15 units of oil 12 units of vinegar 0 units of sugar 1 unit of salt 1 unit of pepper

for a total of 29 units, 15 of which are oil. So the answer is 15/29.
_________________

Nov 2011: After years of development, I am now making my advanced Quant books and high-level problem sets available for sale. Contact me at ianstewartgmat at gmail.com for details.

Re: PS - Salad Dressing Mix Problem [#permalink]
20 Feb 2011, 12:17

Thanks for the replies. I see your answers are correct, similar to what is found in the solutions.

Here is how I interpreted the problem:

Miguel is mixing up a salad dressing. Regardless of the number of servings, the recipe requires that 5/8 of the finished dressing mix be olive oil, 1/4 vinegar, and the remainder an even mixture of salt, pepper and sugar. If Miguel accidentally doubles the vinegar and forgets the sugar altogether, what proportion of the botched dressing will be olive oil?

If he finishes the dressing with 5/8 oil, you'd have:

Where in the problem does it clearly state that he portioned out the oil first, and added it to the vinegar and salt/pepper? Is it possible that "Regardless of the number of servings" means that he's not keeping track of the volume?

I see how you've all arrived at 15/29, but I would have never interpreted the problem that way.

Re: PS - Salad Dressing Mix Problem [#permalink]
20 Feb 2011, 12:38

noodlesalad wrote:

Thanks for the replies. I see your answers are correct, similar to what is found in the solutions.

Here is how I interpreted the problem:

Miguel is mixing up a salad dressing. Regardless of the number of servings, the recipe requires that 5/8 of the finished dressing mix be olive oil, 1/4 vinegar, and the remainder an even mixture of salt, pepper and sugar. If Miguel accidentally doubles the vinegar and forgets the sugar altogether, what proportion of the botched dressing will be olive oil?

If he finishes the dressing with 5/8 oil, you'd have:

Where in the problem does it clearly state that he portioned out the oil first, and added it to the vinegar and salt/pepper? Is it possible that "Regardless of the number of servings" means that he's not keeping track of the volume?

I see how you've all arrived at 15/29, but I would have never interpreted the problem that way.

It is not mentioned anywhere. You are trying to keep the volume(total number of parts) unaltered. It is not mentioned as a constraint in the problem, though. The moment Miguel doubled the quantity of the vinegar and forgot to add sugar; he goofed up both; the proportion of these ingredients in the salad dressing and the volume of the salad dressing.

"Number of servings": Guess means total volume of the entire dressing. It could be 24 parts; 48 parts; 72 parts..etc.
_________________

Re: PS - Salad Dressing Mix Problem [#permalink]
20 Feb 2011, 19:04

Expert's post

noodlesalad wrote:

Thanks for the replies. I see your answers are correct, similar to what is found in the solutions.

Here is how I interpreted the problem:

Miguel is mixing up a salad dressing. Regardless of the number of servings, the recipe requires that 5/8 of the finished dressing mix be olive oil, 1/4 vinegar, and the remainder an even mixture of salt, pepper and sugar. If Miguel accidentally doubles the vinegar and forgets the sugar altogether, what proportion of the botched dressing will be olive oil?

If he finishes the dressing with 5/8 oil, you'd have:

Where in the problem does it clearly state that he portioned out the oil first, and added it to the vinegar and salt/pepper? Is it possible that "Regardless of the number of servings" means that he's not keeping track of the volume?

I see how you've all arrived at 15/29, but I would have never interpreted the problem that way.

The question mentions that he committed two mistakes in the recipe: doubled the vinegar and forgot the sugar. Had he put less olive oil than what the recipe asked for, that would have been another mistake. Let's say he wanted to make 24 ml of dressing. Then the recipe asked for 15 ml olive oil, 6 ml vinegar, 1 ml sugar etc. His mistake was to put double the vinegar (so 12 ml) and no sugar. Had he put 10 ml of olive oil (instead of 15), that would have been yet another mistake and would have been mentioned in the question as such.
_________________

Miguel is mixing up a salad dressing. Regardless of the [#permalink]
21 Oct 2012, 17:12

Incase anyone fell into the trap I did and tried to multiply the Vinegar ratio by two...

i.e.

2/ 8 * 2 = 4/8 = 1/2

This is incorrect, this is from the MGMAT staff...

"Doubling the AMOUNT is not the same as doubling the PERCENTAGE.

Think of it this way. Let's say you're making a sandwich. You like your sandwich to be 1/2 peanut butter and 1/2 jelly. If you double the amount of peanut butter, do you have 100% peanut butter? Of course not. You just have a higher % peanut butter than before.

The easiest route for a problem such as this is to pick some real numbers from the outset. Then double the real number you've picked for the AMOUNT of vinegar, and reinsert that into the total to see what new fraction results. "