aznmexicana wrote:At company A, the average number of years of experience is 9.8 years for male employees and 9.1 years for female employees. What is the ratio of the number of the company's male employees to the number of female employees?
1) There are 52 males at Company A
2) The average number of years of experience for the company's male and female employees is 9.3 years
Step 1 of the Kaplan Method for DS: Analyze the Question Stem
The more complicated the stem, the more time you should spend thinking about it.
Here we're given two sub-averages and asked for the weight of each group. We should immediately think of the weighted average formula:
Overall average = (weight group 1)(average group 1) + (weight group 2)(average group 2)
We have the average of each group. We want the weight of each group. What do we need? The overall average!
Step 2 of the Kaplan Method for DS: Evaluate the Statements
1) # of males, by itself, doesn't give us the weight of the males: insufficient.
2) the overall average! Exactly what we predicted we needed: sufficient.
(2) is sufficient, (1) isn't: choose (B).
* * *
Our takeaways:
1. Whenever a common formula applies to a DS question, jot that formula down on your scrap paper. Identify which part of the formula the question is asking about, which part(s) of the formula you know and which part(s) you need to answer the question.
2. Once you've clearly been given the information you need, don't waste any time actually solving the question! The better you understand the concepts underlying GMAT math, the fewer calculations you'll need to make to confidently select the correct answer.
