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GMAT Diagnostic Test Question 32 Field: word problems (mixture) Difficulty: 700

A Food and Drug lab has two new samples: a 240 gram cup of drip coffee, which contains 124 mg of caffeine, and a 60 gram cup of espresso, containing 160 mg of caffeine. If a technician were to create a new 120 gram cup sample that contained 50% coffee and 50% espresso, how many mg of caffeine would the new drink contain?

A. 111 B. 121 C. 142 D. 191 E. 382
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In the PDF, the question doesn't mention "a new 120 gram cup sample", it just says "combine the two drinks" and therefore is impossible to find the correct answer.
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A new 120 gram cup will contain 50% of coffee and 50% of espresso, that is 60 grams each. 60 grams of espresso contains 160 mg of caffeine, while 60 grams of drip coffee contains \(\frac{124}{4}=31\) mg of caffeine. So, the new drink will contain \(31+160=191\) mg of caffeine.
_________________

In the PDF, the question doesn't mention "a new 120 gram cup sample", it just says "combine the two drinks" and therefore is impossible to find the correct answer.

Thank you. The PDF version is clear now. Technically, we could assume the two drinks were mixed as long as one of them was exhausted, but I think that would not be GMAT-like.
_________________

I'm not sure I would consider this a 700 level question. If all you are doing is dividing the coffee amount by 4 that seems more like <600 level. Perhaps if the mixture were something other than 50/50 where you had to divide the amount in the espresso or something but even then that doesn't seem that complicated.
_________________

If you find this post useful, please give me a kudos. Thanks!

I agree the question seems too straightforward to be 700 level.

Just line up the two proportions

124 mg caffeine / 240g coffee and 160mg caffeine /60g of espresso

the new drink is x/120 and since the drink will comprise 50% coffee and 50% espresso we'll have 60 grams of each so the amount of caffeine from the espresso remains the same and we reduce the coffee fraction to 31 mg of caffeine/ 60 g of coffee and add.

31/60 +160/60= 191 mg of caffeine so the answer is D

@dzyubam- You guys are doing amazing job. I need one suggestion as you so cooly give good explanation for every question. I have realized i can solve any question of quant the only problem is when i m not able to understand it in first 30 seconds i panic. because of that i have messed up my first GMAT attempt. I was scoring 750 in prep tests and on the day of GMAT i scored 610 that may also be because i did not study for 3 months before that. But the problem is I have the technique but i dont know why i do good on one day and worse on some other day. The D day is coming soon. Any suggestion by any one is welcomed.

It seems that the most important task for you would be to stay calm and confident during your Test. Since you can solve the questions just fine, I suggest that you practice in conditions as close to the real GMAT as possible. More practice should do the trick.

I hope other regulars can provide some suggestions.

medha13 wrote:

@dzyubam- You guys are doing amazing job. I need one suggestion as you so cooly give good explanation for every question. I have realized i can solve any question of quant the only problem is when i m not able to understand it in first 30 seconds i panic. because of that i have messed up my first GMAT attempt. I was scoring 750 in prep tests and on the day of GMAT i scored 610 that may also be because i did not study for 3 months before that. But the problem is I have the technique but i dont know why i do good on one day and worse on some other day. The D day is coming soon. Any suggestion by any one is welcomed.

In the PDF, the question doesn't mention "a new 120 gram cup sample", it just says "combine the two drinks" and therefore is impossible to find the correct answer.

Thank you. The PDF version is clear now. Technically, we could assume the two drinks were mixed as long as one of them was exhausted, but I think that would not be GMAT-like.

I downloaded the PDF today and it doesnt mention the 120 g sample part . FYI BTW you guys are absolutely amazing ! This site has been a lifesaver !

Cheers !

gmatclubot

Re: GMAT Diagnostic Test Question 32
[#permalink]
05 Aug 2014, 01:10