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What is the result of multiplying 3/5 by 5/7?
- A. 3/7
- B. 1
- C. 2
- D. 4
Correct Answer: A
Rationale: To multiply fractions, multiply the numerators together and the denominators together. Multiplying 3/5 by 5/7 gives (3*5)/(5*7) = 15/35. This fraction simplifies to 3/7 by dividing the numerator and denominator by their greatest common factor, which is 5. Therefore, the correct answer is 3/7. Choices B, C, and D are incorrect as they do not result from multiplying 3/5 by 5/7.
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Find the area in square centimeters of a circle with a diameter of 16 centimeters. Use 3.14 for π.
- A. 25.12
- B. 50.24
- C. 100.48
- D. 200.96
Correct Answer: D
Rationale: The formula for the area of a circle is: Area = π x (radius²). Given: Diameter = 16 cm, so Radius = Diameter / 2 = 16 / 2 = 8 cm. Now, calculate the area using π = 3.14: Area = 3.14 x (8²) = 3.14 x 64 = 200.96 cm². The correct answer is D (200.96 cm²) as it correctly calculates the area of the circle. Choices A, B, and C are incorrect as they do not represent the accurate area of the circle based on the given diameter and π value.
Apply the polynomial identity to rewrite (a + b)².
- A. a² + b²
- B. 2ab
- C. a² + 2ab + b²
- D. a² - 2ab + b²
Correct Answer: C
Rationale: When you see something like (a + b)², it means you're multiplying (a + b) by itself:
(a + b)² = (a + b) (a + b)
To expand this, we use the distributive property (which says you multiply each term in the first bracket by each term in the second bracket):
Multiply the first term in the first bracket (a) by both terms in the second bracket:
a a = a²
a b = ab
Multiply the second term in the first bracket (b) by both terms in the second bracket:
b a = ab
b b = b²
Now, add up all the results from the multiplication:
a² + ab + ab + b²
Since ab + ab is the same as 2ab, we can simplify it to:
a² + 2ab + b²
So, (a + b)² = a² + 2ab + b².
This is known as a basic polynomial identity, and it shows that when you square a binomial (a two-term expression like a + b), you get three terms: the square of the first term (a²), twice the product of the two terms (2ab), and the square of the second term (b²).
Therefore, the correct answer is C (a² + 2ab + b²)
What is the difference between two negative numbers?
- A. Negative number
- B. Positive number
- C. Zero
- D. Not enough information
Correct Answer: B
Rationale: The correct answer is B: 'Positive number.' When you subtract one negative number from another negative number, the result can be a positive number. For example, the difference between -5 and -3 is 2, which is a positive number. Choice A, 'Negative number,' is incorrect because the result of subtracting two negative numbers can be positive. Choice C, 'Zero,' is incorrect because the difference between two negative numbers is not always zero. Choice D, 'Not enough information,' is incorrect because there is enough information to determine that the difference between two negative numbers can be a positive number.
What is the result of dividing 8 by 4?
- A. 2
- B. 4
- C. 6
- D. 8
Correct Answer: A
Rationale: To find the result of dividing 8 by 4, we divide 8 by 4, which equals 2. Choice B (4) is incorrect because it is the divisor, not the result of the division. Choice C (6) is incorrect as it is not the correct quotient. Choice D (8) is incorrect as it is the dividend, not the result of the division.
Eric buys 5 1/2 pounds of apples each week for four weeks. How many total pounds does he buy?
- A. 22 pounds
- B. 20 pounds
- C. 18 pounds
- D. 24 pounds
Correct Answer: A
Rationale: To find the total pounds of apples Eric buys, you need to multiply the pounds of apples bought each week (5 1/2 pounds) by the number of weeks (4 weeks). When you multiply 5 1/2 by 4, you get 22 pounds. Therefore, the correct answer is A. Choices B, C, and D are incorrect because they do not accurately calculate the total pounds purchased over the four weeks.