DS

[ketkoag]

If the average (arithmetic mean) of the assessed values
of x houses is $212,000 and the average of the assessed
values of y other houses is $194,000, what is the average
of the assessed values of the x+y houses?
(1) x+y=36
(2) x=2y

Here if i put x = 2y in the equation (212000x + 194000y)/(x + y) then y gets canceled and thus we get the average answer.
OA : C, my answer : B

[scoobydooby]

you are spot on ketkoag! whats the source?

https://www.beatthegmat.com/ds2-t13419.html

[ketkoag]

that was from gmat set
thanks
and please lemme know how to search a post before i post the questions.
I was not able to search the same question when i read the instruction in the forum instead got all the other posts that contains all the words from the question and was cumbersome.....

[dwilliams05]

can you simply just replace x=2y into that equation? because the avg of x is sum of x divided by x. In other words what you're referring to x in the denominator isnt the number of x it's the sum of all the x quantities?

Additionally when you take the formula you wrote out 212,000x = 194,000y/x + y, we still dont know what is on the right side of the equal sign? I'm definitely not a math whiz but maybe someone can enlighten me on wheter that is correct or not?