NCERT Solution For Class 8, Maths, Linear Equations In One Variable, Exercise 2.4, involves basic calculations of age related and price related. CBSE class 8 maths ch.2, ex. 2.4 given below.
NCERT Solution For Class 8, Maths, Chapter 2, Exercise 2.4
Exercise 2.4,Class 8, Maths
Q.1. Amina thinks of a number and subtracts $\frac{5}{2}$ from it. She multiplies the result by 8. The result now obtained is 3 times the same number she thought of. What is the number?
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Q.2. A positive number is 5 times another number. If 21 is added to both the numbers, then one of the new numbers becomes twice the other new number. What are the numbers?
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Q.3. Sum of the digits of a two-digit number is 9. When we interchange the digits, it is found that the resulting new number is greater than the original number by 27. What is the two-digit number?
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Q.4. One of the two digits of a two-digit number is three times the other digit. If you interchange the digits of this two-digit number and add the resulting number to the original number, you get 88. What is the original number?
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Q.5. Shobo’s mother’s present age is six times Shobo’s present age. Shobo’s age five years from now will be one third of his mother’s present age. What are their present ages?
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Q.6. There is a narrow rectangular plot, reserved for a school, in Mahuli village. The length and breadth of the plot are in the ratio 11:4. At the rate ₹ 100 per meter it will cost the village panchayat ₹ 75000 to fence the plot. What are the dimensions of the plot?
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Q.7. Hasan buys two kinds of cloth materials for school uniforms, shirt material that costs him ₹ 50 per meter and trouser material that costs him ₹ 90 per meter. For every 3 meters of the shirt material, he buys 2 meters of the trouser material. He sells the materials at 12% and 10% profit respectively. His total sale is ₹ 36,600. How much trouser material did he buy?
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Q.8. Half of a herd of deer are grazing in the field and three fourths of the remaining are playing nearby. The rest 9 are drinking water from the pond. Find the number of deer in the herd.
Ans: Let the total no. of deer = x
According to question,
No. of deer which are Grazing = half of total = $\frac{x}{2}$
Playing = $\frac{x}{2}\times \frac{3}{4}=\frac{3x}{8}$
Drinking water = 9
According to question,
Grazing + playing + drinking = Total no. of deer
⇒ $\frac{x}{2}+\frac{3x}{8}+9=x$
Multiply both sides of equation by 8, we get
⇒ $\left( 8\times \frac{x}{2} \right)+\left( 8\times \frac{3x}{8} \right)+\left( 8\times 9 \right)=8x$
⇒ $4x+3x+72=8x$
⇒ $7x-8x=-72$
⇒ $-x=-72$
⇒ x = 72
Hence, the number of deer in the herd were 72.
Q.9. A grandfather is ten times older than his granddaughter. He is also 54 years older than her. Find their present ages.
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Q.10. Aman’s age is three times his son’s age. Ten years ago, he was five times his son’s age. Find their present ages.
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Chapter 2: Linear Equations In One Variable
- Class 8, Maths, Linear Equations In One Variable, Exercise 2.1
- Class 8, Maths, Linear Equations In One Variable, Exercise 2.2
- Class 8, Maths, Linear Equations In One Variable, Exercise 2.3
- Class 8, Maths, Linear Equations In One Variable, Exercise 2.4
- Class 8, Maths, Linear Equations In One Variable, Exercise 2.5
- Class 8, Maths, Linear Equations In One Variable, Exercise 2.6