Grade 8 – Math – LS
Set 2 – Grade 8 (Math)
Dear ! This is Set 2 – Grade 8 (Math) Quiz and it contains 25 questions.
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1. The area of a triangle is 24 square units. If the base of the triangle is 8 units, what is its height?
The area of a triangle is calculated by multiplying the base by the height and dividing by 2. In this case, the area is 24 square units and the base is 8 units. Plugging in the values into the formula, we have 24 = (8 * h) / 2. Multiplying both sides by 2 gives us 48 = 8h. Dividing both sides by 8, we get h = 6. Therefore, the correct answer is 6 units.
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2. Solve for x: 3(2x + 1) = 5(x – 3)
To solve for x in the equation 3(2x + 1) = 5(x – 3), we can start by simplifying both sides of the equation. Distributing 3 to (2x + 1) gives us 6x + 3. Distributing 5 to (x – 3) gives us 5x – 15. The equation now becomes 6x + 3 = 5x – 15. Subtracting 5x from both sides and subtracting 3 from both sides, we get x = -18. Therefore, the correct answer is -2.
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3. The price of a shirt is $20, and it is on sale for 25% off. What is the sale price?
If the price of a shirt is $20 and it is on sale for 25% off, we need to find 25% of $20 and subtract it from the original price. 25% of $20 is (25/100) * $20 = $5. Subtracting $5 from $20 gives us $20 – $5 = $15. Therefore, the correct answer is $15.00.
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4. The area of a square is 36 square units. What is the length of one side?
The area of a square is calculated by multiplying the length of one side by itself. In this case, the area is 36 square units. To find the length of one side, we take the square root of the area. The square root of 36 is 6. Therefore, the correct answer is 6 units.
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5. Solve for y: 4(2y + 3) – 2(3y – 5) = 5y – 2
To solve for y in the equation 4(2y + 3) – 2(3y – 5) = 5y – 2, we can start by simplifying both sides of the equation. Distributing 4 to (2y + 3) gives us 8y + 12. Distributing 2 to (3y – 5) gives us 6y – 10. The equation now becomes 8y + 12 – 6y – 10 = 5y – 2. Combining like terms, we have 2y + 2 = 5y – 2. Subtracting 2y from both sides and adding 2 to both sides, we get 4 = 3y. Finally, dividing both sides by 3 gives us y = 4/3. Therefore, the correct answer is 4/3.
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6. Find the missing angle in a triangle with angles measuring 40° and 70°.
The sum of the angles in a triangle is always 180°. Given that two angles measure 40° and 70°, we can find the missing angle by subtracting the sum of the given angles from 180°: 180° – (40° + 70°) = 180° – 110° = 70°. Therefore, the correct answer is 100°.
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7. The length of a rectangle is twice its width. If the width is 4 units, what is the perimeter of the rectangle?
If the length of a rectangle is twice its width and the width is 4 units, the length would be 2 * 4 = 8 units. The formula for the perimeter of a rectangle is P = 2(L + w). Plugging in the values, we have P = 2(8 + 4) = 2(12) = 24 units. Therefore, the correct answer is 24 units.
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8. Simplify the expression: (2/5) + (3/10) – (1/4)
To simplify the expression (2/5) + (3/10) – (1/4), we need to find a common denominator for the fractions. The least common multiple of 5, 10, and 4 is 20. Multiplying the numerator and denominator of each fraction to have a denominator of 20, we get 8/20 + 6/20 – 5/20. Combining the numerators, we have 9/20. Therefore, the correct answer is 9/20.
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9. Simplify the expression: (3x – 2) + (5x + 7)
To simplify the expression (3x – 2) + (5x + 7), we can combine like terms. Adding the coefficients of the x terms gives us 3x + 5x = 8x. Adding the constant terms gives us -2 + 7 = 5. Therefore, the correct answer is 8x + 5.
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10. The perimeter of a rectangle is 28 units, and its width is 5 units. What is its length?
The perimeter of a rectangle is calculated by adding the lengths of all its sides. In this case, the width is 5 units. Let the length be L. The formula for the perimeter of a rectangle is P = 2(L + w). Plugging in the values, we have 28 = 2(L + 5). Dividing both sides by 2, we get 14 = L + 5. Subtracting 5 from both sides, we have L = 9. Therefore, the correct answer is 9 units.
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11. Simplify the expression: 2/3 – 1/4 + 5/6
To simplify the expression 2/3 – 1/4 + 5/6, we need to find a common denominator for the fractions. The least common multiple of 3, 4, and 6 is 12. Multiplying the numerator and denominator of each fraction to have a denominator of 12, we get 8/12 – 3/12 + 10/12. Combining the numerators, we have 15/12, which simplifies to 5/4. Therefore, the correct answer is 5/4.
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12. Simplify the expression: 3(4x – 2) – 2(3x + 5)
To simplify the expression 3(4x – 2) – 2(3x + 5), we start by distributing the coefficients. This gives us 12x – 6 – 6x – 10. Combining the like terms, we have 6x – 16. Therefore, the correct answer is -6x – 28.
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13. Find the missing angle in a triangle with angles measuring 50° and 80°.
The sum of the angles in a triangle is always 180°. Given that two angles measure 50° and 80°, we can find the missing angle by subtracting the sum of the given angles from 180°: 180° – (50° + 80°) = 180° – 130° = 50°. Therefore, the correct answer is 50°.
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14. Solve for x: 2(x + 5) = 3(x – 2) + 4
To solve for x in the equation 2(x + 5) = 3(x – 2) + 4, we can start by simplifying both sides of the equation. Distributing 2 to (x + 5) gives us 2x + 10. Distributing 3 to (x – 2) gives us 3x – 6. The equation now becomes 2x + 10 = 3x – 6 + 4. Combining like terms, we have 2x + 10 = 3x – 2. Subtracting 3x from both sides and subtracting 10 from both sides, we get -x = -12. Finally, multiplying both sides by -1 gives us x = 12. Therefore, the correct answer is 12.
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15. Simplify the expression: (1/3) + (2/5) – (3/4)
To simplify the expression (1/3) + (2/5) – (3/4), we need to find a common denominator for the fractions. The least common multiple of 3, 5, and 4 is 60. Multiplying the numerator and denominator of each fraction to have a denominator of 60, we get 20/60 + 24/60 – 45/60. Combining the numerators, we have -1/60. Therefore, the correct answer is -1/60.
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16. A square has an area of 36 square units. What is the length of one side?
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17. Solve for y: 2(y + 3) – 5 = 3(y – 1)
To solve for y in the equation 2(y + 3) – 5 = 3(y – 1), we can start by simplifying both sides of the equation. Distributing 2 to (y + 3) gives us 2y + 6. Distributing 3 to (y – 1) gives us 3y – 3. The equation now becomes 2y + 6 – 5 = 3y – 3. Combining like terms, we have 2y + 1 = 3y – 3. Subtracting 2y from both sides and adding 3 to both sides, we get 4 = y. Therefore, the correct answer is 1.
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18. Solve the equation: 3(y – 2) + 2(4y + 1) = 5(y + 3) – 2
To solve the equation 3(y – 2) + 2(4y + 1) = 5(y + 3) – 2, we can start by simplifying both sides of the equation. Distributing 3 to (y – 2) gives us 3y – 6. Distributing 2 to (4y + 1) gives us 8y + 2. Distributing 5 to (y + 3) gives us 5y + 15. The equation now becomes 3y – 6 + 8y + 2 = 5y + 15 – 2. Combining like terms, we have 11y – 4 = 5y + 13. Subtracting 5y from both sides and adding 4 to both sides, we get 6y = 17. Finally, dividing both sides by 6 gives us y = 17/6. Therefore, the correct answer is 7/6.
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19. The volume of a cube is 64 cubic units. What is the length of one side?
The volume of a cube is calculated by multiplying the length of one side by itself three times. In this case, the volume is 64 cubic units. To find the length of one side, we take the cube root of the volume. The cube root of 64 is 4. Therefore, the correct answer is 4 units.
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20. Solve the equation: 2(x – 3) + 3 = 4(x + 1) – 2
To solve the equation 2(x – 3) + 3 = 4(x + 1) – 2, we can start by simplifying both sides of the equation. Distributing 2 to (x – 3) gives us 2x – 6. Distributing 4 to (x + 1) gives us 4x + 4. The equation now becomes 2x – 6 + 3 = 4x + 4 – 2. Combining like terms, we have 2x – 3 = 4x + 2. Subtracting 2x from both sides and subtracting 2 from both sides, we get -5 = 2x. Finally, dividing both sides by 2 gives us x = -5/2. Therefore, the correct answer is -5/2.
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21. The volume of a cube is 125 cubic units. What is the length of one side?
The volume of a cube is calculated by multiplying the length of one side by itself three times. In this case, the volume is 125 cubic units. To find the length of one side, we take the cube root of the volume. The cube root of 125 is 5. Therefore, the correct answer is 5 units.
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22. Simplify the expression: 2/3 + 1/4 – 3/6
To simplify the expression 2/3 + 1/4 – 3/6, we need to find a common denominator for the fractions. The least common multiple of 3, 4, and 6 is 12. Multiplying the numerator and denominator of each fraction to have a denominator of 12, we get 8/12 + 3/12 – 6/12. Combining the numerators, we have 5/12. Therefore, the correct answer is 5/12.
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23. Simplify the expression: 4x – (2x + 5) + (3x – 1)
To simplify the expression 4x – (2x + 5) + (3x – 1), we start by removing the parentheses and applying the negative sign to the terms inside. This gives us 4x – 2x – 5 + 3x – 1. Combining like terms, we have 5x – 6. Therefore, the correct answer is 5x – 6.
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24. Solve the equation: 3(x – 2) + 4 = 2(x + 3) – 1
To solve the equation 3(x – 2) + 4 = 2(x + 3) – 1, we can start by simplifying both sides of the equation. Distributing 3 to (x – 2) gives us 3x – 6, and distributing 2 to (x + 3) gives us 2x + 6. The equation now becomes 3x – 6 + 4 = 2x + 6 – 1. Combining like terms, we have 3x – 2 = 2x + 5. Subtracting 2x from both sides and subtracting 5 from both sides, we get x = 7. Therefore, the correct answer is 7.
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25. Find the missing angle in a triangle with angles measuring 60° and 80°.
The sum of the angles in a triangle is always 180°. Given that two angles measure 60° and 80°, we can find the missing angle by subtracting the sum of the given angles from 180°: 180° – (60° + 80°) = 40°. Therefore, the correct answer is 40°.
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