in a competitive exam there are 90 multipr chaice que. 4 marks are awarded for every correct ans. 2 marks are dedeucted for every wrong ans and 0.5 marks is deducted for every inatempted que from the total scare of correct ans if a student leaves 10 que ans scores total of 195 marks . how many of his ans were correct,?
Answers
Answer:
60 Answers were correct.
Step-by-step explanation:
Given Data:
Total number of Question= 90
For every correct Answer=+4
For every wrong answer=-2
For every unattempt question=-0.5
IF,
A Student leaves 10 questions(let z be the no of questions)=>(Zx0.5) -0.5 x 10=-5 marks
Total Marks scored by the student=195
Let x be the number of correct answer
Let y be the number of incorrect answer=>Y=(90-Z)-X { 90 - z because in that number we will get the unattempted question too so we remove it from the total.), then we subtract it by the no of correct answer to get Incorrect answer. This we do to get all variables as same terms.
So the equation will be
X x +4 + Y x -2 + (Z x -0.5) = 195 (∵ Z x-0.5=-5 marks)
So we get
X x +4 + Y x -2 + -5 = 195
X x +4 + Y x -2 = 195 +5
X x +4 + Y x -2 = 200
X x +4 + ({90-Z) - x) x -2 = 200 (∵Y=(90-Z)-X )
X x +4 + ({90-10) - x) x -2 = 200 (∵Z=10)
+4x + ({80) - x) x -2 = 200
+4x + (-160+2 x) = 200
+4x + -160+2 x = 200
+4x +2 x = 200 +160
6x=360
X=360÷6
X=60
Hence the number of correct answer are 60.
Hope this helps you!