Given:
A test has 10 questions worth 100 points.
Points of each multiple choice question = 4
Points of each open-response question = 12
To find:
The number of multiple choice questions.
Solution:
Let x be the number of multiple choice questions and y be the open-response questions.
According to the question,
Total question : [tex]x+y=10[/tex] ...(i)
Total points : [tex]4x+12y=100[/tex] ...(ii)
Form (i), we get
[tex]y=10-x[/tex] ...(iii)
Putting this in (ii), we get
[tex]4x+12(10-x)=100[/tex]
[tex]4x+120-12x=100[/tex]
[tex]-8x=100-120[/tex]
[tex]-8x=-20[/tex]
Dividing both sides by -8, we get
[tex]x=\dfrac{-20}{-8}[/tex]
[tex]x=2.5[/tex]
Since x is the number of multiple choice questions, so it cannot be a faction value.
Therefore, the number of multiple choice questions in test are either 2 or 3.
