SOLUTION: A company has 22 employees. Twelve of these employees have masters degrees and fifteen have at least one Microsoft Certification and three have neither a Microsoft certificat

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Question 1021884: A company has 22 employees. Twelve of these
employees have masters degrees and fifteen
have at least one Microsoft Certification and
three have neither a Microsoft certification
nor a masters degree.
How many have both a Masters degree and a
certification?

Found 2 solutions by Edwin McCravy, ikleyn:
Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!

Everybody in the red circle M have masters.
Everybody in the blue circle C have certification.

a = the number of employees who have a masters but no certification
b = the number of employees who have both a masters and a certification
c = the number of employees who have a certification but no masters
d = the number of employees who have neither a masters nor a 
certification
A company has 22 employees.
 
a+b+c+d = 22

Twelve of these employees have masters degrees
 
a+b = 12

and fifteen have at least one Microsoft Certification
 
b+c = 15

and three have neither a Microsoft certification nor a masters
degree.
 
d = 3

So we have this system of four equations and 4 unknowns:

system%28a%2Bb%2Bc%2Bd+=+22%2Ca%2Bb+=+12%2Cb%2Bc+=+15%2Cd+=+3%29

Solve by substitution or elimination.

Subtract the 2nd equation from the first, get c+d=10.
Substitute d=3, get c=7.  Substitute c=7 in b+c=15,
get b=8.  Substitute b=8 in a+b=12, get a=4.

How many have both a Masters degree and a certification?
That's b = 8.



Edwin

Answer by ikleyn(52776) About Me  (Show Source):
You can put this solution on YOUR website!
.
For this kind of problems see the lesson Counting elements in sub-sets of a given finite set in this site.