Gmat prep

[awilhelm]

At a certain company, the average 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

[DanaJ]

1. is not sufficient, since we do not know anything about the number of women working in the company. It could very well be 100 women with an experience of 9.1 years each or 2 women with 9.1 years of experience each.
2. Let's say m = no. of men and w = no. of women.
We have the following equations:
Total years of experience for men: 9.8*m
Total years of experience for women: 9.1*w
Total years of experience for everybody: 9.8m + 9.1w = 9.1(m+w) + 0.7m. This means that the average years of experience will be [9.1(m+w)+0.7m]/(m+w) = 9.1 + 0.7m/(m+w) = 9.3. So 0.7m/(m+w) = 0.2.. This in turn is equivalent to:
0.7m = 0.2m + 0.2w
0.5m = 0.2w
Therefore, the ratio of men to women is 5 : 2.

Answer: B