(i) Critical Thinking Write two different algebraic expressions f… - Vidyadip

Question

(i) Critical Thinking Write two different algebraic expressions for the word phrase
$\left(\frac{1}{4}\right)$ of the sum of $x$ and 7.
(ii) What's the Error? A student wrote an algebraic expression for "5 less than a number n divided by $3^{\prime \prime}$ as $\frac{n}{3}-5$. What error did the student make?
(iii) Write About If Shashi used addition to solve a word problem about the weekly cost of commuting by toll tax for ₹15 each day. Ravi solved the same problem by multiplying. They both got correct answer. How is this possible?

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Answer

(i) First expression $=\frac{1}{4}(x+7)$
As we know, the addition is commutative.
So, it can also be written as = $\frac{1}{4}(7+x)$
(ii) Since, the expression of 5 less than a number n
= n - 5
So, 5 less than a number n divided by 3 will be written = $\frac{n-5}{3}$
So, student makes an error of quotient.
(iii) By addition method,
Total weekly cost = 15 + 15 + 15 + 15 + 15 + 15 + 15 = ₹105
By multiplication method,
Total weekly cost = Cost of one day × Seven days
= 15 × 7 = ₹105

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