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.

(a) 12 incorrect answers

(b) 17 incorrect answers

Explanation:

Given

Let the correct answer be x,

incorrect answers be y

unattempted be z

So, the equation is:

Solving (a):

Given

Required

Calculate y

becomes

Collect like terms

Solving (b):

Required

Calculate y

becomes

Collect Like Terms

answer: in october 1962, an american u-2 spy plane secretly photographed nuclear missile sites being built by the soviet union on the island of cuba. president kennedy did not want the soviet union and cuba to know that he had discovered the missiles. he met in secret with his advisors for several days to discuss the problem.

explanation:

adopted the practice of proskynesis, a persian court custom that involved bowing down and kissing the hand of others, depending on their rank.