GreenlightTestPrep wrote:
The Sargon Corporation offers an optional stock-option buy in program to its employees. Of the employees with salaries greater than or equal to $100K, 85% choose to participate in this plan. Of the employees with salaries less than $100K, 77% choose to participate in this plan. Which of the following could be the total number of employees? Answer choices below:
A) 100
B) 200
C) 350
D) 460
E) 525
F) 640
G) 750
H) 880
We can solve this using the
Double Matrix methodKeep the word count down to a minimum, let's refer to the employees earning more than or equal to $100,000 a year as RICH employees, and refer to the other employees as POOR employees.
Let
x = the total number of RICH employees
Let
y = the total number of POOR employees
So,
x+y = the TOTAL number of employees
This also means
0.85x = the number of RICH employees participating in the program
And
0.77y = the number of POOR employees participating in the program
We get the following:
Key concept:
0.85x and
0.77y must be POSITIVE INTEGERS
0.85x = (85/100)x = (17/20)x = 17x/20If
17x/20 is a POSIIVE INTEGER, then
x must be a multiple of 20 0.77y = (77/100)y = 77y/100If
77y/100 is a POSIIVE INTEGER, then
y must be a multiple of 100 Since
x+y = the TOTAL number of employees, we're looking for answers choices such that the total number of employees can be expressed as (
some positive multiple of 20) + (
some positive multiple of 100)
A) 100 --> we can't rewrite 100 in the form (
some positive multiple of 20) + (
some positive multiple of 100)
B) 200 =
(5)(20) +
(1)(100) GREAT!
C) 350 --> we can't rewrite 350 in the form (
some positive multiple of 20) + (
some positive multiple of 100)
D) 460 =
(3)(20) +
(4)(100) GREAT!
E) 525 --> we can't rewrite 525 in the form (
some positive multiple of 20) + (
some positive multiple of 100)
F) 640 =
(2)(20) +
(6)(100) GREAT!
G) 750 --> we can't rewrite 750 in the form (
some positive multiple of 20) + (
some positive multiple of 100)
H) 880 =
(4)(20) +
(8)(100) GREAT!
Answer: B, D, F, H
Cheers,
Brent