On marking correctly one question a boy gets 5 marks and 2 marks are deducted on marking a wrong response. He attempted 85 questions but got 285 marks. How many did he mark correctly?
Answers
Let the boy attempted "x" correct questions and "85-x"incorrect questions.
Since the boy gets 5 marks for each correct question and 2 marks are deducted for each incorrect question, therefore
5x - 2(85-x) = 285
5x - 170 + 2x = 285
7x = 285 + 170
7x = 455
x = 455÷7
x = 65
Therefore the right answers attempted by boy are 65...
Answer:
65 Questions he mark correctly
Step-by-step explanation:
Let say number of questions he marked correctly = X
He attempted 85 Questions
So Question Marked by him incorrectly = 85 - X
Marks received for Correctly Marking the Questions = 5X
Marks Deducted for Incorrectly Marking the Questions = 2(85-X) = 170 - 2X
Net Marks Obtained = 5X - (170 -2X) = 7X -170
He got 285 Marks
=> 7X -170 = 285
=> 7X = 285 + 170
=> 7X = 455
=> X = 65
65 Questions he mark correctly