Problem Solving

hey guys i dont have the explanations for answers for OG 11 so if u guys can help me out wid these problems that i got stuck in? Thanks in advance...

196.
The Ratio, by volume of soap to alcohol to water in a certain solution is 2:50:100. The solution will be altered so that the ratio of soap to alcohol is doubled while the ratio of soap to water is halved. If the altered solution will contain 100 cubic centimeters of alcohol, how many centimeters of water will it contain?

197.
If 75 percent of a class answered the first question on a certain test correctly, 55 percent answered the second question on the test correctly, and 20 pecent answered neither of the questions correctly, what percent answered both correctly?

Until these problems i was breezing through the questions....but i guess my brain stopped working...and im waaaay confused....pls help?

Are the answers as given below

196:400

197: 50

@ adpandey .. welcome to the forum

Please do provide the answer choices and also please try and post one question per thread.

Regards

1.
Ratio sw is 2:50:100

s:a doubled so new ratio is 4:50
s:w halfed, so new ratio 1:100 or 4:400
So, sw is 4:50:400

If the solution has 100 a
then sw is 8800

Ans 800

2.
Lets take number of students = 100
A = 75 (First ans correct)
B = 55 (second ans Correct)
A intersection B = 20
100 - 20 = 80

So, 75 + 55 - 80 = 50

Ans 50

is there a way to set this og . 197 question into a double matrix chart that is explained in the manhattan gmat way?

I only use Venn Diagrams for the 2 variables and would really like to see how this question is done through a double matrix chart.

Enginpasa1 wrote:is there a way to set this og . 197 question into a double matrix chart that is explained in the manhattan gmat way?

I only use Venn Diagrams for the 2 variables and would really like to see how this question is done through a double matrix chart.

Information Given
..................................FirstCorrect.........FirstNotCorrect.......Total

SecondCorrect...................X................................................55

SecondNotCorrect........................................20

Total................................75...............................................100



Fill in the blanks. Solve for X.

..................................FirstCorrect.........FirstNotCorrect.......Total

SecondCorrect..................50.......................5.......................55

SecondNotCorrect.............25.......................20......................45

Total................................75.......................25.....................100


X=50