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The order of operations (PEMDAS) dictates the sequence for evaluating mathematical expressions. If a = 2 and b = -3, what is the value of 3a^2 - 2ab + b^2?
- A. -3
- C. 33
- D. 15
Correct Answer: C
Rationale: Given expression: 3a^2 - 2ab + b^2. Substitute the values of a and b: 3(2)^2 - 2(2)(-3) + (-3)^2 = 3(4) + 12 + 9 = 12 + 12 + 9 = 24 + 9 = 33. Therefore, the value of the expression is 33, which corresponds to option C. Options A, B, and D are incorrect as they do not accurately evaluate the expression with the given values of a and b.
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What is 70% of 65?
- A. 40.5
- B. 45.5
- C. 50
- D. 55
Correct Answer: B
Rationale: To find 70% of 65, you multiply 0.7 by 65. Mathematically, 0.7 * 65 = 45.5. Therefore, the correct answer is 45.5. Choice A (40.5) is incorrect because it is not the result of multiplying 0.7 by 65. Choice C (50) is incorrect as it is higher than the correct answer. Choice D (55) is also higher than the correct result and is therefore incorrect.
If 1 pound equals 453.59 grams, how many grams would a 7 lb. baby weigh?
- A. 3175.13 grams
- B. 4000 grams
- C. 4535 grams
- D. 3500 grams
Correct Answer: A
Rationale: To convert pounds to grams, multiply the weight in pounds by the conversion factor of 453.59 grams per pound. Therefore, 7 pounds x 453.59 grams/pound = 3175.13 grams, which is the weight of a 7 lb. baby in grams. Choice A is correct. Choice B (4000 grams) is incorrect as it does not use the correct conversion factor. Choice C (4535 grams) is incorrect as it seems to have used a rounding error. Choice D (3500 grams) is incorrect as it does not apply the correct conversion factor.
Express the number 1906 in Roman numerals.
- A. MCMIV
- B. MCMVI
- C. MDCCCCVI
- D. MCMVII
Correct Answer: B
Rationale: To convert 1906 to Roman numerals, break it down into components: 1000 (M), 900 (CM), 6 (VI), resulting in MCMVI. Therefore, the correct Roman numeral representation for 1906 is MCMVI. Choice A (MCMIV) is incorrect as it represents 1904. Choice C (MDCCCCVI) is incorrect because it uses the subtractive notation incorrectly, and it's considered nonstandard. Choice D (MCMVII) is incorrect as it represents 1907, not 1906.
What is the boiling point of water?
- A. 100°C
- B. 98°C
- C. 99°C
- D. 102°C
Correct Answer: A
Rationale: The correct answer is 100°C (Choice A). The boiling point of water is the temperature at which it changes from a liquid to a gas. Under normal atmospheric pressure, water boils at 100°C. Choices B, C, and D are incorrect because they do not represent the standard boiling point of water. 98°C, 99°C, and 102°C do not correspond to the temperature at which water boils under normal conditions.
A farmer wants to plant trees at the outside boundaries of his rectangular field with dimensions 650 meters 780 meters. Each tree requires 5 meters of free space all around it from the stem. How much free area will be left?
- A. 478,800 m²
- B. 492,800 m²
- C. 507,625 m²
- D. 518,256 m²
Correct Answer: A
Rationale: To calculate the area taken by the trees, we need to account for the space each tree requires. Each tree needs 5 meters of free space all around it, totaling 10 meters added to each dimension. Therefore, the new dimensions of the field are (650-10) meters by (780-10) meters. Calculating the area of the new field: (640m 770m = 492,800m²). To find the free area remaining, subtract the new field's area from the original field's area: 507,000m² - 492,800m² = 14,200m². Therefore, the free area left after planting the trees is 14,200m². Choice A is the correct answer as it represents the free area left after planting the trees.