Question

In an objective examination of 90 questions, 5 marks are allotted for every correct answer and 2 marks are deducted for every wrong answer. After attempting all the 90 questions, a student got a total of 387 marks. find the number of questions that he attempted wrong. select one:

a. 9
b. 27
c. 36
d. 18

Answer 1

The student got 9 questions wrong on the exam. By setting up equations for correct and incorrect answers and solving simultaneously, we find that the student attempted 9 questions incorrectly. Thus, the student got 9 questions wrong on the exam, which is option (a).

Step-by-step explanation:

To determine the number of questions a student attempted wrong on an examination where 5 marks are awarded for every correct answer and 2 marks are deducted for every incorrect answer, we can set up an equation using the total mark scored and the total number of questions. Let's denote the number of correct answers as x and the number of wrong answers as y.

Given that there are 90 questions:

• x + y = 90

For the marking scheme:

• (5 × correct answers) - (2 × wrong answers) = total marks scored,
• 5x - 2y = 387

With two equations:

• x + y = 90
• 5x - 2y = 387

we can solve for x and y simultaneously. On solving we find:

• 5x + 5y = 450 (by multiplying the first equation by 5)
• 5x - 2y = 387 (second equation as is)

Subtracting the second equation from the first:

• 5y + 2y = 450 - 387
• 7y = 63
• y = 63 / 7
• y = 9

Thus, the student got 9 questions wrong on the exam, which is option (a).