Question

In a competitive examination one mark is awarded for each correct answer while 1/2 mark is deducted for every wrong answer . Jayanthi answered 120 questions and got 90 marks. How many questions did she answered correctly.

Answer 1

$\bf\huge\underline\fcolorbox{red}{yellow}{Answer = 100}$

$\bf\huge\underline{Explaination :-}$

Let the number of correct answers be x then the number of wrong answers be (120 - x)

Then, by given condition,

x × 1 - (120 - x) × $\dfrac{1}{2}$ = 90

=> x - 60 + $\dfrac{x}{2}$ = 90

=> $\dfrac{3x}{2}$ = 150

Therefore, x = $\dfrac{150 × 2}{3}$ = 50 × 2 = 100

Hence, Jayanthi answered correctly 100 questions.

Answer 2

Step-by-step explanation:

• LET THE TOTAL NO OF CORRECT ANSWER JAYANTHI ANSWERED BE = X
• LET THE WRONG ANSWERS BE= Y
• TOTAL QUE SHE ANSWERED = 120
• TOTAL MARKS SHE GOT = 90

So; = X + Y = 120- EQ 1

• MARKS GOT FOR RIGHT ANSWERS = 1
• MARKS DEDUCTED FOR WRONG ANSWERS = 1/2

= 1(X) - 1/2(Y) = 90

• TAKE LCM AND YOU WILL GET EQ

= 2X-Y = 180 EQ 2

• ADDING EQ 1 AND 2

= X + Y = 120

= 2X - Y = 180

-----------------------

= 3X = 300

=X = 100

ANS = TOTAL QUE SHE ANSWERED CORRECTLY = 100

THANK YOU

BY SHUBHAM BATRA

LIKE IF YOU UNDESTAND THE QUE EASILY

I TRIED MY BEST