Arithmetic Mean Word Problem

[vongdn]

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 in 9.3 years.


ANSWER --> State (2) alone is sufficient.


I see that (1) is sufficient, but how is (2) sufficient?

[neerajkumar1_1]

Please post DS questions in the right thread...

REquest moderator to change the thread for this question.. .

FOr the soln...

Given:
mean for male = 9.8
mean for female = 9.1

question ratio of number of male to number of female...

statement 1)
doesnt help estgablish anything abt fmale.. .
insufficient

Statement 2)

avg of both is 9.3

Now u shud rem Avg = sum/n
so sum= Avg *n

here 9.3(total number of emp) = (9.8 * number of men) + (9.1 * number of female)

Also = total numberof emp = number of male + number of females...

so 9.3(number of male + number of females) = (9.8 * number of men) + (9.1 * number of female)


Hence u can find the ratio...

Sufficient...

IMO: B

Hope this helps!!

[limestone]

Hi,

(1) mentions nothing about no. of female, or the relationship between no. of male and that of female
Then it's clearly insuff.

(2) gives us the average number of years of experience for the company's male and female employees

Let's call:
the no. of male employees : x
the no. of female employees : y

Now we have:

(x*9.8 + y*9.1) / (x+y) = 9.3
or 9.8x +9.1y = 9.3x + 9.3y
or 0.5x = 0.2y
Then x/y = 2/5

Thus 2 is suff.

Pick B

[Rahul@gurome]

Let the number of male employees in the company be m and number of female employees be 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.
Consider first statement (1) alone.
It means m = 52, but we need more information to get m : f.
So (1) alone is not sufficient.
Next consider (2) alone.
It means (9.8m + 9.1f)/(m+f) = 9.3.
Or 9.8m + 9.1f = 9.3m + 9.3f.
Or 0.5m = 0.2f
Or m/f = m : f = 2 : 5.
So (2) alone is sufficient