Math Problem

[Oscar_LaVista]

math problem-
a class has an average grade of 70%. another class has an average grade of 92%. when you add both classes together, the average grade is 85%. How many students in each class?

[Dan]

There are an infinite number of possibilities, but the ratio students of the second class is 2.14285714286 times the number of students in the first class.

[Dan]

Here is how I set up the equation to solve the problem:  0.7X + 0.92Y = 0.85(X + Y)

X = the number of students in the first class
Y = the number of students in the second class

[wvit1001]

how you going to solve that equation dan?   you've only got 1 equation with 2 unknowns.

[Dan]

You can combine like values to come up with a ratio between the two numbers.  That's why I said there are an infinite number of possibilities, but the ratio is fixed.  The second class has 2.14 times the number of students of the first class.

But you are right, we cannot know how many students are in either class until we know how many students are in one of the classes.

[Truman62]

I saw the answer and it is completely screwy to me.

I see why no one gets it.

Since it is a multiple choice question, MAYBE someone can guess it.

[takncarabizniz]

[Oscar_LaVista]

dan's ratio is right.  the answer is infinite, but it has to be in multiples of 30 students in the democratic class, and 14 students in the republican class, in order to have whole numbers of students. 

[Dan]

I see why no one gets it.

I got it.  There is no single finite answer.  The answer is a ratio - 2.14

[Oscar_LaVista]

the ratio is right but you did not solve the problem.  you did not say how many students were in the democratic (92% average grade) or the republican class (70% average grade).  the fact you think just getting the ratio correctly is answering the question is kinda weird.  go back and read the question....

[Dan]

If the LCD is 30, then the answer is 3,000 democrats and 6,420 Republicans.

the ratio is right but you did not solve the problem.

Yes I did.  There are an infinite number of possibilities.  That is the answer.  I could provide several examples, each of which meet the criteria.

you did not say how many students were in the democratic or the republican class

Because there is no single answer that meets the criteria.

the fact you think just getting the ratio correctly is answering the question

Nope.  The first thing I said was there are an infinite number of answers.  The common factor among all the answers is the ratio 2.14.

go back and read the question....

Go back and read my answer where I said there are an infinite number of answers.  You must have missed that part.

[Dan]

0.07Y = 0.15X