DAV Class 7 Maths Chapter 7 Value Based Questions
Linear Equations in One Variable Value Based Questions
1. Aman is an avid reader. He has a good collection of books. In his summer vacation he read a book of 300 pages in four days.
(a) If the number of pages he read on the second, third, and fourth day is half the number of pages he read on the previous day, find the number of pages he read on the first day.
Solution
\begin{align*} \text{Let no. of pages he reads on first day } & = \color{green} x \\ \text{No. of pages he reads on second day } & = x \times \frac{1}{2} \implies \color{green} \frac{x}{2} \\ \text{No. of pages he reads on third day } & = \frac{1}{2} \times \frac{x}{2} \implies \color{green} \frac{x}{4} \\ \text{No. of pages he reads on fourth day } & = \frac{1}{2} \times \frac{x}{4} \implies \color{green} \frac{x}{8} \\ \\ \text{Total pages read in 4 days} & = 300 \\ \\ \color{magenta} x + \frac{x}{2} + \frac{x}{4} + \frac{x}{8} &= \color{magenta}300 \\ \\ \frac{x {\color{green} \times 8}}{1 {\color{green} \times 8}} + \frac{x {\color{green} \times 4}}{2 {\color{green} \times 4}} + \frac{x {\color{green} \times 2}}{4 {\color{green} \times 2}} + \frac{x}{8} &= 300 \\ \\ \frac{8x + 4x + 2x + x}{8} & = 300 \\ \\ \frac{15x}{8} &= 300 \\ \\ x &= \frac{\cancel{300}^{20} \times 8}{\cancel{15}_1} \\ \\ x &= 160 \ pages \\ \end{align*}
Answer No. of pages Aman reads on first day \( = \color{red} 160 \ pages. \)
(b) Discuss the importance of reading books.
Answer Reading books improves vocabulary.
2. Students of Rotary Club prepared 'Tie and Dye Dupattas', 'Wall Hangings' and 'Hand Bags' for sale in an Exhibition to help the poor people. They earned a total profit of ₹2000.
(a) If the profit on Dupattas is ₹30 less than two times the profit on Wall Hangings and the profit on Hand Bags is ₹80 more than twice the profit on Wall Hangings, find the profit on Wall Hangings.
Solution
\begin{align*} \text{Let profit on Wall Hangings } &= x \\ \text{Profit on Dupattas} &= 2x - 30 \\ \text{Profit on Hand Bags} &= 2x + 80 \\ \text{Total profit} & = 2000 \\ \\ \color{magenta}x + (2x - 30) + (2x + 80) &= \color{magenta}2000 \\ x + 2x - 30 + 2x + 80 &= 2000 \\ 5x + 50 &= 2000 \\ 5x &= 2000 - 50 \\ 5x &= 1950 \\ x &= \frac{\cancel{1950}^{390}}{\cancel5_1} \\ \\ x &= \text{₹ } 390 \\ \end{align*}
Answer Profit on Wall Hangings \( = \color{red} \text{₹} 390\).
(b) What value is exhibited by the students?
Answer Helping and caring towards poor people.