In a competitive examination, one mark is awarded for each correct answer while 1/2 mark is deducted for every wrong answer. Jayanti answered 120 questions and got 90 marks. How many questions did she answer correctly?NCERT Class XMathematics - Exemplar ProblemsChapter _PAIR OF LINEAR EQUATIONS IN TWO VARIABLES
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Answered by
11
LET x be the no. Of Questions she answered correctly
and y be no. Of Questions she answered incorrectly
Therefore 1st eq is:- x-1/2y=90
and 2nd eq is:-x+y=120.
Solve them to get value of x.
and y be no. Of Questions she answered incorrectly
Therefore 1st eq is:- x-1/2y=90
and 2nd eq is:-x+y=120.
Solve them to get value of x.
Answered by
15
total answers is equal to 120
the number of correct answer is equal to 'x'
no. of wrong answers is equal to (120-x)
marks awarded for each right answer is =1
marks awarded for x right answers is 1*x=x
marks deducted for each wrong answer=0.5
then the marks deducted for (120-x) right answers is=(120-x )0.5=60-0.5x...
the marks she will get is=
=x-(60-0.5x)
=x-60+0.5x
=1.5x-60
she has got 90 marks so..
1.5x-60=90
=1.5x=150
x=150/1.5
x=100...
so she did 100 questions correctly..
my dear frnd I hope this helps u a lote.. pls make as brainlist... pls..
the number of correct answer is equal to 'x'
no. of wrong answers is equal to (120-x)
marks awarded for each right answer is =1
marks awarded for x right answers is 1*x=x
marks deducted for each wrong answer=0.5
then the marks deducted for (120-x) right answers is=(120-x )0.5=60-0.5x...
the marks she will get is=
=x-(60-0.5x)
=x-60+0.5x
=1.5x-60
she has got 90 marks so..
1.5x-60=90
=1.5x=150
x=150/1.5
x=100...
so she did 100 questions correctly..
my dear frnd I hope this helps u a lote.. pls make as brainlist... pls..
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