Guys I was solving a question and I made this silly mistake.I corrected myself but was hoping somebody throw some light on where my concept was wrong.
Suppose 2/3 out of N employees dring regular coffee.Out of these 2/5 add cream.How many of the employees who drink regular coffee do not add cream?
Ans: 2/3n  2/5n = 4n/15.(ans.)
What I did was:If 2/5 add cream,then 3/5 do not add cream.So 3/5 x 2/3n = 2/5n
I made this mistake while solving a ques.Throw some light?
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2/3*n drink Regular Coffee.uptowngirl92 wrote:Guys I was solving a question and I made this silly mistake.I corrected myself but was hoping somebody throw some light on where my concept was wrong.
Suppose 2/3 out of N employees dring regular coffee.Out of these 2/5 add cream.How many of the employees who drink regular coffee do not add cream?
Ans: 2/3n  2/5n = 4n/15.(ans.)
What I did was:If 2/5 add cream,then 3/5 do not add cream.So 3/5 x 2/3n = 2/5n
2/5*2/3*n Add cream
(2/34/15)*n do not add cream.

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.Out of these 2/5 add cream In that case what is "out of these? "niramay wrote:You took (2/5th fraction of 2/3rd of N) to get the no. of ppl who add cream to Regular Coffee, whereas the problem expected you to get the same as 2/5N (without multiplying it with 2/3N).

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I prefer picking numbers in this type of question. Make N=15, then 10 drink coffee and 5 don't. From those who drink coffee, 2/5 add cream ==> 4 add cream
Now go through the answer options and plug in 15 to see were you get 4 as an answer.
Now go through the answer options and plug in 15 to see were you get 4 as an answer.

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That would work too. My point was that the question stem was not clear.shibal wrote:I prefer picking numbers in this type of question. Make N=15, then 10 drink coffee and 5 don't. From those who drink coffee, 2/5 add cream ==> 4 add cream
Now go through the answer options and plug in 15 to see were you get 4 as an answer.
Do 2/5 out of N add cream or 2/5 out of 2/3 out of N add cream.

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According to me out of these refers to the whole sentence preceding it.shibal wrote:it says 'out of these, 2/5 add cream.....' so you can imply that he is talking about the 3/5 that drink coffee
this is correct if the question is about those adding cream!shibal wrote:I prefer picking numbers in this type of question. Make N=15, then 10 drink coffee and 5 don't. From those who drink coffee, 2/5 add cream ==> 4 add cream
Now go through the answer options and plug in 15 to see were you get 4 as an answer.
however, ur way is correct and he should use 6 instead of 4 to verify his correct formula since the question is about who do not add cream..
so, 2/5 x 10 = 6
2/5 N is the right answer.
r u sure that u did a mistakeuptowngirl92 wrote:Guys I was solving a question and I made this silly mistake.I corrected myself but was hoping somebody throw some light on where my concept was wrong.
Suppose 2/3 out of N employees dring regular coffee.Out of these 2/5 add cream.How many of the employees who drink regular coffee do not add cream?
Ans: 2/3n  2/5n = 4n/15.(ans.)
What I did was:If 2/5 add cream,then 3/5 do not add cream.So 3/5 x 2/3n = 2/5n
ur answer is right! enjoy!
I don't think I'm understanding the question correctly.uptowngirl92 wrote:Suppose 2/3 out of N employees dring regular coffee.Out of these 2/5 add cream.How many of the employees who drink regular coffee do not add cream?
(a) It asks how many of the employees who drink regular coffee (a subset of all employees, spec 2/3x) do not add cream.
(b) It states that of this subset, 2/5 add cream.
(c) Therefore, 3/5 of this subset must not add cream.
The way this question is phrased makes me think that 3/5 is the answer...
If the question was asking how many employees drink regular coffee AND do not add cream, then it would be 2/5.