I have 40 questions, 4 marks given for a correct answer, 2 marks deducted for each wrong answer and 1 mark deducted for for each answer not attempted I attempt 19 and score 25 marks.how many questions did I get right
Let x be the no. of questions I got right and y be the no. of question I got wrong.
So,
x+y=40........(1)
&
4x-2y-21=25
4x-2y=46
2x-y=23........(2)
comparing equations (1) and (2)
3x=63
x=21......(3)
putting the value of equation (3) in equation (1)
21+y=40
y=19
So, 21 questions I got right
No. of Attempt question =19
No. Of unattemt question=21
No. Of right question = x
No. Of wrong question =19-x
From question ,
4x-(19-x)2- 21=25
On solving
X= 14
To determine how many questions you got right, we need to calculate the total marks obtained for the 19 questions you attempted.
First, let's calculate the total marks deducted for wrong answers and unanswered questions. For each wrong answer, 2 marks are deducted, and for each unanswered question, 1 mark is deducted.
Total marks deducted for wrong answers: 2 marks x (19 - number of correct answers)
Total marks deducted for unanswered questions: 1 mark x (40 - 19 - number of correct answers)
Since you obtained 25 marks with the 19 questions attempted, we can set up the equation:
Correct answers x 4 - Total marks deducted = 25 marks
Now, let's plug in the values:
Correct answers x 4 - [2 marks x (19 - correct answers) + 1 mark x (40 - 19 - correct answers)] = 25 marks
Simplifying the equation:
4 correct answers - 2(19 - correct answers) - (40 - 19 - correct answers) = 25 marks
4 correct answers - 38 + 2 correct answers - 21 + correct answers = 25 marks
7 correct answers - 59 = 25 marks
7 correct answers = 25 marks + 59
7 correct answers = 84 marks
Therefore, you got 84/7 = 12 correct answers out of the 19 questions attempted.