there are 120 question, 1 mark for a correct answer, - 1/2 Mark for wrong answer, - 1/4 Mark for unattempted question. Of 5 mark will get, then how many are incorrect answer.
If Mark got a score of 5, then if x were right and y were wrong, and z left blank,
x+y+z = 120
x - y/2 - z/4 = 5
Since there are only two equations, there is no unique solution.
But, given that
y = 5(x-28)
z = 260-6x
You can see that x >= 28 and z <= 43
Now make a table starting with x=28 and see what y has to be.
To find the number of incorrect answers, let's first calculate the total marks obtained.
Given:
Correct answer = 1 mark
Incorrect answer = -1/2 mark
Unattempted question = -1/4 mark
Total marks obtained = 5
Let's assume the number of correct answers as C, incorrect answers as I, and unattempted questions as U.
Since each correct answer gives 1 mark:
Total marks obtained from correct answers = C * 1 = C
Since each incorrect answer deducts 1/2 mark:
Total marks obtained from incorrect answers = I * (-1/2) = -I/2
Since each unattempted question deducts 1/4 mark:
Total marks obtained from unattempted questions = U * (-1/4) = -U/4
Adding all three:
C - I/2 - U/4 = 5
Now, let's solve this equation to find the number of incorrect answers (I).
To eliminate the fractions, let's multiply both sides of the equation by 4 to get rid of the denominators:
4C - 2I - U = 20
We don't know the values of C and U, so we need some additional information to proceed further.