Question

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

Answer 1

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.

Answer 2

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..