15.4k views
9 votes
4. In a competitive examination, (+4)

marks are given for every correct
answer, (-2) marks are given for every
incorrect answer and 0 marks for not
attempting the question.
a) Ruchi scored 20 marks. If she
has got 12 correct answers, how
many questions has she attempted
incorrectly?
b) Rohit scored(-6 )marks in this test .Through he has got 7 correct answers .How many questions has he attempted incorrectly.

User DariusV
by
7.0k points

1 Answer

1 vote

Answer:

(a) 12 incorrect answers

(b) 17 incorrect answers

Step-by-step explanation:

Given


Correct = +4


Wrong = -2


Unattempted = 0

Let the correct answer be x,

incorrect answers be y

unattempted be z

So, the equation is:


Marks = 4x - 2y + 0 * z


Marks = 4x - 2y

Solving (a):

Given


Marks = 20


x = 12

Required

Calculate y


Marks = 4x - 2y becomes


20 = 4 * 12 - 2 y


20 = 48 - 2 y

Collect like terms


2y = 48 - 20


2y = 28


y = 12

Solving (b):


Marks = -6


x = 7

Required

Calculate y


Marks = 4x - 2y becomes


-6 = 4 * 7 - 2y


-6 = 28 - 2y

Collect Like Terms


2y = 28 + 6


2y = 34


y = 17

User Koronis Neilos
by
6.8k points