Data Sufficiency

gughanbose wrote:At a certain company, the average (arithmetic mean) number of years of experience is 9.8 years for the male employees and 9.1 years for the female employees. What is the ratio of the number of the company's male employees to the number of the company's female employees?

(1) There are 52 male employees at the company.
(2) The average number of years of experience for the company's male and female employees combined is 9.3 years.

Let us assume the number of male employees in the company is m and number of female employees is f. Average number of years of experience for male employees is 9.8 and average number of years of experience for female employees is 9.1.
We need the ratio m:f.

Statement 1: m = 52
This is not enough to determine the ratio of m:f.

Not sufficient.

Statement 2: (9.8m + 9.1f)/(m + f) = 9.3
--> 9.8m + 9.1f = 9.3m + 9.3f.
--> 0.5m = 0.2f
--> m/f = m : f = 2:5

Sufficient

The correct answer is B.

gughanbose wrote:Which method is the best one ?

Weighted average and alligation are often the same method under different names and explained a bit differently. When they are actually different, both have their advantages and disadvantages.

It is you who should choose the method which works for you the best.
As usual my suggestion is do not to stick to one particular method. That way you'll end up sticking to a method which works best for a particular problem but not so good (often fails) for other problems on the same concept. Most of the problems in GMAT can be solved in more than method. Solve any problem with as much methods as you can. Only then you'll learn the trick of always identifying the best method.

For example, for this the best method that works for me is : if I know the weighted average of two quantity A and B, and the values of A and B, I can find out the ratio of the weights of A and B. So, as soon as I read the statement 2, I know it is sufficient. No algebra, no calculation, nothing. I'll just read the statement, mark the answer, and move on.

But others may not find this as the best method as they may not know "What is weighted average?" or "How can one conclude that?".