In a test with 75 , 2 points were deducted for each wrong answer and 3 points were added for every correct answer.
How many were answered correctly if the score was zero?
Answers
Answer:
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Explanation:
The trick here is to take a ratio of the inverse of marks for coreect and incorrect itself to get the no. of questions answered correctly or incorrectly.
No. of correct answers : no. of incorrect answers
= 1/4 : 1/2.5
= 2.5 : 4
= 5 : 8
As the total no. of questions is 13 so no. of correct answers will be 5.
Validate and confirm-
Correct = 5 x 4 = 20
Incorrect = 8 x -2.5 = -20
Thus final score 0
Answer :
Total number of questions answered correctly if the score was zero = 30
Given :
• Total questions in a test = 75
• Total points deducted for each wrong answer = 2
• Total points added for each correct answer = 3
To find :
• Number of questions answered correctly if the score was zero
Solution :
Let us assume the total questions which were answered correctly as x. And the total incorrectly answered questions as 75 - x.
According to the conditions given :-
→ 3x - 2(75 - x)
According to the question,
→ 3x - 2(75 - x) = 0
→ 3x - 150 + 2x = 0
→ 5x - 150 = 0
→ 5x = 150
→ x = 150 ÷ 5
→ x = 30
→ The value of x = 30
Therefore, the total number of questions which were answered correctly = x = 30