Ratios

[mengnu.liang]

Two questions taken from 1,037 Practice questions for the New GMAT

The ratio of SUVs to passenger cars sold at a particular automobile dealership has been declining from 2003 to 2007, while total sales have reamined constant. The total number of vehicles sold in 2007 was dividisle by 10. In 2007, were more cars sold than SUVs?

1) If in 2007 as many SUVs had been sold as cars were sold in 2003, there would have been a 36% increase in total vehicle sales.

2) In 2003, twice as many SUVs were sold as cars.

the answer is A. But, I had to use excel spreadsheet to list out all possible scenarios to make sure Statement 1 works. Could you please let me know if you know a better way?

Q2: The afternoon after a party, Traci prepares a cleaning solution of x liters of water and y liters of bleach. The bleach comes in half-liter containers. How many such containers will Traci require for her cleaning solution?

1) Traci will need a total of 25 liters of solution altogether.

2) To halve the concentration of bleach in her solution, Trace would need to add 2.4y liters of water, and reduce the number of liters of bleach by 1.

The answer is C. Still can't figure out how you get the answer since we don't know what the original water:bleach ratio was.

Thank you very much.

[tim]

I'm going to pass on these because of the source. If you get a problem from a random source and find that you have to set up a spreadsheet to solve it, chances are you're not doing anything wrong and the question is just inappropriate. You'll do yourself a favor by sticking to sources that are as close to the GMAT as possible, such as the GMAT Prep software and our CAT exams. Please let us know if you have any questions about problems from these sources and we'll be glad to help you!

[mengnu.liang]

I'm going to pass on these because of the source. If you get a problem from a random source and find that you have to set up a spreadsheet to solve it, chances are you're not doing anything wrong and the question is just inappropriate. You'll do yourself a favor by sticking to sources that are as close to the GMAT as possible, such as the GMAT Prep software and our CAT exams. Please let us know if you have any questions about problems from these sources and we'll be glad to help you!

Hi ,

Thank you for your reply. The question was taken from a study book from Princeton Review.

[tim]

Right. I would definitely recommend you stick to official GMAT questions and MGMAT materials. As you saw from that first question, material from other sources may just not provide the practice you need on appropriate questions..

[krishnan.anju1987]

Ok, This is how I sorted it out..

a) gives that water and bleach total volume. We cannot find the individual volume of bleach

b) without knowing the total volume of bleach and water, we would just have an equation with two variables, cannot be solved and hence insufficient.

Now, consider both the statements

Water Bleach Concentration of bleach
x y y/(x+y) =y/25
x+2.4 y-1 y-1/(x+2.4+y-1)
= y-1/(25+1.4)

hence, concentration of bleach after tweaking the solution is y-1/26.5
but as mentioned in the problem, this concentration is half that of the previous concentration

hence,
(y-1)/26.4=y/50

hence, y can be found out and this can help us find the number of containers required by doubling the value of y.

hence answer is C

Let me know if my approach is right.

the first problem as you mentioned was too tedious. All I could do was eliminate B but solving a took some time.

[tim]

i'll leave it to other students to comment on this, and will reiterate my point that the best way to avoid wasting your time is to stick to our questions and those released by the GMAT..