# Class 9 Math Masters: Conquer The Quiz Challenge!

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Janaisa Harris, BA-Mathematics |
Mathematics Expert
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Ms. Janaisa Harris, an experienced educator, has devoted 4 years to teaching high school math and 6 years to tutoring. She holds a degree in Mathematics (Secondary Education, and Teaching) from the University of North Carolina at Greensboro and is currently employed at Wilson County School (NC) as a mathematics teacher. She is now broadening her educational impact by engaging in curriculum mapping for her county. This endeavor enriches her understanding of educational strategies and their implementation. With a strong commitment to quality education, she actively participates in the review process of educational quizzes, ensuring accuracy and relevance to the curriculum.
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Are you ready to embark on an exciting journey through the Class 9 Math Quiz? Mathematics can seem like a complex puzzle, but it's a captivating world of patterns and logic waiting to be explored. By understanding its applications and recognizing the elegance of solving equations, you can unlock its true potential. This quiz is designed to gauge your knowledge of ninth-grade math concepts and challenge your problem-solving skills. Are you prepared to take on the challenge and demonstrate your mathematical prowess? Let's dive in and see how well you fare in this fascinating world of numbers and equations

## Class 9 Math Quiz Questions and Answers

• 1.

### A is 40% of B. What percentage is B of A?

• A.

60%

• B.

140%

• C.

250%

• D.

160%

C. 250%
Explanation
When A is 40% of B, it means A equals 40% (or 0.4 times) B. To find what percentage B is of A, we reverse the relationship, calculating 1 divided by 0.4, which equals 2.5. This means B is 250% of A, indicating B's value is 2.5 times larger than A's value.

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• 2.

### X+5=10. Then x equals:

• A.

5

• B.

10

• C.

15

• D.

-5

A. 5
Explanation
The equation x+5=10 can be solved by subtracting 5 from both sides of the equation. This gives us x=10-5, which simplifies to x=5. Therefore, the value of x that satisfies the equation is 5.

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• 3.

### X2+4x+3=0; Then x equals:

• A.

2 or 3

• B.

-1 or -3

• C.

1 or 3

• D.

5 or -1

B. -1 or -3
Explanation
The given equation x^2 + 4x + 3 = 0 can be factored as (x + 1)(x + 3) = 0. Therefore, x can be equal to -1 or -3, as these are the values that make the equation true.

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• 4.

### What is the next number in the sequence: 3, 7, 15, 31, ?

• A.

47

• B.

63

• C.

72

• D.

58

B. 63
Explanation
The given sequence is increasing, and each number is obtained by doubling the previous number and then adding 1.
Starting with 3:
3 * 2 + 1 = 7
7 * 2 + 1 = 15
15 * 2 + 1 = 31
To find the next number, we apply the same pattern:
31 * 2 + 1 = 63
So, the next number in the sequence is 63.

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• 5.

### Y2+ 4=20. Then y equals:

• A.

4 only

• B.

-4 only

• C.

4 or -4

• D.

16

C. 4 or -4
Explanation
The equation y^2 + 4 = 20 can be rewritten as y^2 = 16 by subtracting 4 from both sides. Taking the square root of both sides gives us y = 4. Therefore, y is 4 or -4 only.

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• 6.

### The price of an item increases by 20% and then decreases by 20%. So the price has:

• A.

Increased by 4%

• B.

Decreased by 4%

• C.

Increased by 0%

• D.

Increased by 40%

B. Decreased by 4%
Explanation
The price of the item actually decreases. Hereâ€™s why:
Letâ€™s say the original price of the item is \$100.
If the price increases by 20%, it becomes \$120 (\$100 + 20% of \$100).
Then, if this new price decreases by 20%, it becomes \$96 (\$120 - 20% of \$120).
So, even though the percentage increase and decrease are the same, the price of the item is less than the original price because the decrease is applied to a larger amount than the increase. Therefore, the price of the item has decreased.

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• 7.

### The ratio of girls: boys in a school is 5:7. If there are 525 girls, how many boys are there?

• A.

375

• B.

625

• C.

735

• D.

325

C. 735
Explanation
The ratio of girls to boys in the school is 5:7. This means that for every 5 girls, there are 7 boys. If there are 525 girls, we can calculate the number of boys by setting up a proportion. We can write the proportion as 5/7 = 525/x, where x represents the number of boys. Cross-multiplying, we get 5x = 7 * 525, which simplifies to 5x = 3675. Dividing both sides by 5, we find that x = 735. Therefore, there are 735 boys in the school.

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• 8.

### David and John share \$455 in the ratio of 2:3, respectively. How much money does John get?

• A.

\$182

• B.

\$273

• C.

\$91

• D.

\$175

B. \$273
Explanation
David and John share the money in the ratio of 2:3. To find out how much money John gets, we need to calculate 3 parts of the ratio. Since the total number of parts is 5 (2+3), we divide the total amount of money (\$455) into 5 equal parts. Each part is worth \$91. Multiplying this by 3 gives us \$273, which is the amount of money John gets.

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• 9.

### X-12y = 0. Then y/x equals:

• A.

1/6

• B.

12

• C.

1/12

• D.

None

C. 1/12
Explanation
The given equation is x-12y=0. To find the value of y/x, we need to isolate y. By rearranging the equation, we get y = x/12. Therefore, y/x is equal to (x/12)/x, which simplifies to 1/12. Hence, the answer is 1/12.

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• 10.

### Change 3/20 into a decimal:

• A.

0.3

• B.

0.5

• C.

0.15

• D.

1.5

C. 0.15
Explanation
To change a fraction into a decimal, we divide the numerator (3) by the denominator (20). So, 3 divided by 20 equals 0.15. Therefore, the correct answer is 0.15.

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• 11.

### Write 68/0.00001 as an ordinary number.

• A.

6800000

• B.

680000

• C.

68000

• D.

0.00068

A. 6800000
Explanation
To express the fraction 68/0.00001 as an ordinary number, you can perform the division:
68 ÷ 0.00001
Converting the decimal value into fraction, we get:
68 ÷ 1/100000 = 68 * 100000 = 6800000
So, 68/0.00001 is equal to 6,800,000 as an ordinary number.

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• 12.

### 4*4-2*(-3)+6= ?

• A.

17

• B.

28

• C.

-36

• D.

None

B. 28
Explanation
To solve the expression 4 * 4 - 2 * (-3) + 6 using the BODMAS (Brackets, Order, Division and Multiplication, Addition and Subtraction) rule:
First, evaluate the multiplication and division from left to right:
4 * 4 = 16
-2 * (-3) = 6 (The double negative becomes a positive)
Now, rewrite the expression with the results: 16 + 6 + 6
Finally, perform the addition from left to right: 16 + 6 = 22
22 + 6 = 28
So, 4 * 4 - 2 * (-3) + 6 = 28.

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• 13.

### When you reduce \$ 80 by 11%, you will get:

• A.

\$8.80

• B.

\$71.20

• C.

\$69

• D.

None

B. \$71.20
Explanation
When you reduce \$80 by 11%, you are subtracting 11% of \$80 from \$80. To calculate this, you multiply \$80 by 11% (which is 0.11) to get \$8.80. Then, you subtract \$8.80 from \$80 to get \$71.20. Therefore, the correct answer is \$71.20.

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• 14.

### Write 0.67543 correct to 2 significant figures.

• A.

0.68

• B.

0.7

• C.

0.67

• D.

0.70

A. 0.68
Explanation
The given number, 0.67543, has 5 significant figures. Rounding it to 2 significant figures means we need to keep only the first two significant figures and round the rest. The third significant figure, 5, is less than 5, so we round down. Therefore, the correct answer is 0.68.

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• 15.

### Simplify 5ab-7ba+4ab=?

• A.

2ab

• B.

-2ab

• C.

16ab

• D.

None

A. 2ab
Explanation
The given expression involves adding and subtracting common terms. In this case, we have 5ab, -7ba, and 4ab. By rearranging the terms, we can combine the like terms. The -7ba can be rewritten as -7ab since the order of the variables does not matter. Adding 5ab and 4ab gives us 9ab. Therefore, the simplified expression is 9ab - 7ab, which simplifies further to 2ab.

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• 16.

### Solve 4(x+2)=24

• A.

X=11/2

• B.

X=4

• C.

X=-4

• D.

X=16

B. X=4
Explanation
The equation 4(x+2)=24 can be solved by first distributing the 4 to both terms inside the parentheses, resulting in 4x + 8 = 24. Next, we can subtract 8 from both sides of the equation to isolate the variable, giving us 4x = 16. Finally, we divide both sides of the equation by 4 to solve for x, which gives us x = 4.

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• 17.

### The sum of the three consecutive even numbers is 222. Find the numbers.

• A.

73,74,75

• B.

74,74,74

• C.

72,74,76

• D.

None

C. 72,74,76
Explanation
The correct answer is 72, 74, 76. The sum of three consecutive even numbers can be found by adding the first even number to the third even number and then adding the result to the second even number. In this case, 72 + 76 + 74 equals 222, which matches the given sum. Therefore, 72, 74, and 76 are the three consecutive even numbers that add up to 222. In the option, 73,74,75, all these are not even numbers. In the other option, 74, 74, 74, consecutive numbers are not present.

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• 18.

### The gradient of the line joining (-4,-1) and (4,2) is:

• A.

-3/8

• B.

3/8

• C.

0

• D.

8/3

B. 3/8
Explanation
The gradient of a line is determined by the change in y divided by the change in x between two points on the line. In this case, the change in y is 2 - (-1) = 3 and the change in x is 4 - (-4) = 8. Therefore, the gradient is 3/8.

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• 19.

### The gradient of the line y = 4 -2x is:

• A.

4

• B.

2

• C.

-2

• D.

None

C. -2
Explanation
The gradient of a line represents its steepness or slope. In the given equation, y = 4 - 2x, the coefficient of x (-2) represents the slope of the line. Since the coefficient is negative, the line has a negative slope. Therefore, the gradient of the line y = 4 - 2x is -2.

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• 20.

### The gradient of the line x+3y=9 is

• A.

3

• B.

1/3

• C.

-1/3

• D.

None

C. -1/3
Explanation
The gradient of a line can be determined by rearranging the equation into the form y = mx + c, where m is the gradient. In this case, rearranging x + 3y = 9 gives y = (-1/3)x + 3, which means that the coefficient of x (-1/3) is the gradient of the line. Therefore, the correct answer is -1/3.

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• 21.

### If 2x-3y +4x-7y=0, then the value of y/x is:

• A.

3/5

• B.

5/3

• C.

5/11

• D.

-3/5

A. 3/5
Explanation
2x - 3y + 4x - 7y = 0
Combining like terms:
(2x + 4x) - (3y + 7y) = 0
6x - 10y = 0
Now, let's solve for y in terms of x:
10y = 6x
y = (6/10)x
Simplify the fraction:
y = (3/5)x
So, the value of y/x is 3/5.

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• 22.

### If 2x+5y=18 and x=2, what is the value of 4x+5y:

• A.

20

• B.

19

• C.

22

• D.

21

C. 22
Explanation
To find the value of 4x+5y, we substitute the given value of x into the equation 2x+5y=18. This gives us 2(2)+5y=18, which simplifies to 4+5y=18. By subtracting 4 from both sides of the equation, we get 5y=14. Dividing both sides by 5, we find that y=14/5. Now, we substitute the values of x and y into the expression 4x+5y, which gives us 4(2)+5(14/5)=8+14=22. Therefore, the correct answer is 22.

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• 23.

### Factor the quadratic expression: x2+x-30:

• A.

(x+5)(x-6)

• B.

(x-5)(x+6)

• C.

(x-6)(x-5)

• D.

None

B. (x-5)(x+6)
Explanation
The given quadratic expression, x^2 + x - 30, can be factorized as (x - 5)(x + 6). This can be determined by finding two numbers that multiply to give -30 and add up to 1, which are -5 and 6 in this case. Therefore, the correct answer is (x - 5)(x + 6).

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• 24.

### Change 36 km/h to meters per second:

• A.

20

• B.

10

• C.

36

• D.

None

B. 10
Explanation
To convert kilometers per hour to meters per second, we need to multiply the value by 1000/3600. In this case, 36 km/h is equivalent to 10 meters per second.

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Janaisa Harris |BA-Mathematics |
Mathematics Expert
Ms. Janaisa Harris, an experienced educator, has devoted 4 years to teaching high school math and 6 years to tutoring. She holds a degree in Mathematics (Secondary Education, and Teaching) from the University of North Carolina at Greensboro and is currently employed at Wilson County School (NC) as a mathematics teacher. She is now broadening her educational impact by engaging in curriculum mapping for her county. This endeavor enriches her understanding of educational strategies and their implementation. With a strong commitment to quality education, she actively participates in the review process of educational quizzes, ensuring accuracy and relevance to the curriculum.

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• Current Version
• Apr 03, 2024
Quiz Edited by
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Expert Reviewed by
Janaisa Harris
• Dec 04, 2010
Quiz Created by
Imthiyas Slasa

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