YOU ARE GEMIN YOU ARE DIS SATISFIED WITH THE BOOK PUBLISHED BY NCERT WRITE A LETTER TO THE DIRECTOR NCERT NEW DELHI COMPLAINING AGAINST THE BOOK
Answers
Explanation:
Answer :-
\: \: \underline{\boxed{\bf{\mapsto \: \: Firstly \: let's \: understand \: the \: concept \: used}}}
↦Firstlylet
′
sunderstandtheconceptused
Here the concept of Linear Equations in Two Variables has been used. According to this, we can find the required two unknown values. We can make the value of one, dependent on other so that we can find them both . Now we can form equations from this question and find the answer. Let's do it !!
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★ Question :-
Hermaan scored 40 marks in a test, getting 4 marks for each right answer and losing 1 mark for each wrong answer. If the number of questions he answered wrongly is 1 less than the number of questions he answered correctly, then find the number of questions he answered.
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★ Solution :-
Given,
» Marks scored by Hermaan = 40
» Marks for every right answer = 4
» Marks for every wrong answer = -1 (since marks get deducted)
Marks for every wrong answer = -1 (since marks get deducted) » No of question he answered correct = 1 + Number of answer he answered wrong
• Let the number of wrong answers be y
• Let the number of right answers be x
• Then, total number of answers attempted by Hermaan = x + y
According to the question :-
~ Case I :-
⌬ 4x - y = 40
⌬ y = 4x - 40 ... (i)
~ Case II :-
⌬ x = 1 + y ... (ii)
From equation, (i) and (ii), we get,
⌬ x = 1 - 40 + 4x
⌬ x - 4x = -39
⌬ -3x = -39
\: \: \huge{\boxed{\rm{\Longrightarrow \: \: \: x \: = \: \dfrac{\not{-} \: 39}{\not{-} \: 3} \: = \: 13}}}
⟹x=
−3
−39
=13
\: \: \huge{\boxed{\sf{x \: = \: 13}}}
x=13
• Hence, correct answers done by Hermaan = 13
Using equation (ii) and the value of x, we get,
⌬ x = 1 + y
⌬ y = x - 1
⌬ y = 13 - 1 = 12
\: \: \huge{\boxed{\sf{y \: = \: 12}}}
y=12
Now we got the values of x and y.
⌬ Total number of answers attempted by Hermaan = x + y
⌬ Total number of answers attempted by Hermaan = 13 + 12 = 52
\: \: \underline{\boxed{\rm{\mapsto \: \: Thus, \: total \: number \: of \: answers \: attempted \: by \: Hermaan \: are \: \underline{\underline{52}} \: and \: correct \: answers \: done \: by \: Hermaan \: \underline{\underline{13}}}}}
↦Thus,totalnumberofanswersattemptedbyHermaanare
52
andcorrectanswersdonebyHermaan
13
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\: \: \underline{\boxed{\sf{\mapsto \: \: Confused? \: Don't \: worry \: let's \: verify \: it}}}
↦Confused?Don
′
tworrylet
′
sverifyit
For verification we need to simply apply the values we got into our equations.
~ Case I :-
=> 4x - y = 40
=> 4(13) - 12 = 40
=> 52 - 12 = 40
=> 40 = 40
Clearly, LHS = RHS.
=> x = y + 1
=> 13 = 12 + 1 = 13
Clearly, LHS = RHS
Here both the conditions satisfy, so our answer is correct.
Hence, Verified.
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\: \: \underline{\underline{\boxed{\rm{Let's \: know \: more \: :-}}}}
Let
′
sknowmore:−
• Linear Equations are the equations formed using constant and variable terms of single degrees.
• Polynomials are the equations formed using constant and variable terms but can be of many degrees.
• Linear Equations in Two Variables are the equations formed using two unknown variables, whose values are found out simultaneously