The number of questions answered correctly = 90.
<h3>What is a system of linear equations?</h3>
- A system of linear equations is a set of two or more linear equations.
- Linear equations refer to the equations that involve two or more variables in the form of "ax + b".
Now,
Given:
- Total number of questions = 200
- Marks for correct answer = 4
- Marks for incorrect answer = -1
- Total marks = 250
To find : Number of correct answers = ?
Finding:
Now, assuming that the student attempted and answered all the questions,
- Let the number of questions correctly answered be x and incorrectly answered be y.
Then,
- x + y = 200 (For number of questions) (eqn 1)
- and 4x - y = 250 (For the marks scored) (eqn 2)
Solving the system of linear equations:
For eqn 2, we get that y = 4x - 250
Substituting in eqn 1, we get:
=> x + 4x - 250 = 200
=> 5x = 250 + 200 = 450
=> x = 90
That is, the number of questions answered correctly = 90, the incorrect answers = 200 - 90 = 110.
To learn more about system of linear equations, refer to the link: brainly.com/question/2226590
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