patrannn wrote:

Each employee in a certain task force is either a manager or a director. What percent of the employee on the task force are directors ?

1.The Average salary of the Managers on the task force is $5000 less than the avg salary of all Employees on the task force.

2.The avg salary of the directors on the task force is $15000 greater than the avg salary of all employees on the task force.

a)

b)

c)

d)

e)

I got C

Set S = average salary of all

Sm = average salary of managers

Sd = average salary of directors

d = number of directors

m = number of managers

We are looking for:

d / (m+d) = ?

The equation of average salary is the following:

S = (m*Sm + d*Sd) / (m+d)

In (1), we know that Sm = S-5000, and plug it back in, you get no where.

In (2), same problem as (1).

If using both conditions, we have:

S = (m*(S-5000) + d*(S+15000)) / (m+d) = (m*S - 5000m + d*S + 15000d) / (m+d)

S = (S*(m+d) - 5000m + 15000d) / (m+d) = S +(15000d - 5000m)/(m+d)

0 = (15000d - 5000m)/(m+d)

15000d = 5000m

3d = m

And so, d / (m+d) = d / (3d + d) = 1/4

SUFFICIENT