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question:Calculate the value of (3 times 4 times 5)left(frac{1}{3} + frac{1}{4} + frac{1}{5}right). text{(A)} 40 qquad text{(B)} 47 qquad text{(C)} 50 qquad text{(D)} 55 qquad text{(E)} 60

answer:1. **Calculate the new product of integers**: [ 3 times 4 times 5 = 60 ] 2. **Compute the sum of the new fractions**: [ frac{1}{3} + frac{1}{4} + frac{1}{5} ] Find a common denominator, which is the least common multiple of 3, 4, and 5, equal to 60: [ frac{1}{3} = frac{20}{60}, quad frac{1}{4} = frac{15}{60}, quad frac{1}{5} = frac{12}{60} ] Adding these, [ frac{20}{60} + frac{15}{60} + frac{12}{60} = frac{47}{60} ] 3. **Multiply the product of integers by the sum of fractions**: [ 60 times frac{47}{60} = 47 ] 4. **Conclusion**: The expression evaluates to 47. Thus, the final answer is 47. The correct answer is boxed{text{(B)} 47}.

question:Determine the number of integers n satisfying [1+leftlfloordfrac{120n}{121}rightrfloor=leftlceildfrac{119n}{120}rightrceil.]

answer:Define [ g(n) = leftlceil frac{119n}{120} rightrceil - leftlfloor frac{120n}{121} rightrfloor. ] We need to find when g(n) = 1. Consider shifting n by the least common multiple of 120 and 121, which is 14520: [ g(n + 14520) = leftlceil frac{119 (n + 14520)}{120} rightrceil - leftlfloor frac{120 (n + 14520)}{121} rightrfloor = leftlceil frac{119n}{120} + 119 rightrceil - leftlfloor frac{120n}{121} + 120 rightrfloor. ] Simplify this as [ leftlceil frac{119n}{120} rightrceil + 119 - leftlfloor frac{120n}{121} rightrfloor - 120 = leftlceil frac{119n}{120} rightrceil - leftlfloor frac{120n}{121} rightrfloor - 1 = g(n) - 1. ] This indicates that g(n + 14520) = g(n) - 1. For each residue class modulo 14520, there is a unique integer n such that g(n) = 1. Thus, the answer is boxed{14520}.

question:Eight cubes, whose volumes are 1, 27, 64, 125, 216, 343, 512, and 729 cubic units, are alternately stacked vertically to form a tower, starting with the largest at the bottom. The side lengths thus are cube roots of these volumes, i.e., 1, 3, 4, 5, 6, 7, 8, and 9 units respectively. The cubes are arranged such that the largest and smallest alternately follow one another from the bottom. Calculate the total visible surface area of the tower (including the bottom). textbf{(A)} 1368qquadtextbf{(B)} 1408qquadtextbf{(C)} 1450qquadtextbf{(D)} 1500

answer:1. **Identify the side lengths of the cubes**: The side lengths of these cubes are 1, 3, 4, 5, 6, 7, 8, and 9 units, with the largest at the bottom. 2. **Determine the visible faces for each cube**: - The bottom cube (side length 9) has all its faces visible except the top face, contributing 5 faces. - The second cube from bottom (side length 8) has all faces visible except the bottom face, contributing 5 faces because it is larger than the cube on top of it. - The cube above (side length 7) has its top and side faces visible, contributing 5 faces. - Continue this pattern, with each cube revealing all but the bottom face until the top cube. 3. **Calculate the surface area of each cube**: - Bottom cube (side length 9): 5 times 9^2 = 5 times 81 = 405 - Second cube (side length 8): 5 times 8^2 = 5 times 64 = 320 - Third cube (side length 7): 5 times 7^2 = 5 times 49 = 245 - Continue the pattern, summing the areas. 4. **Compute the total surface area**: - Total surface area = 405 + 320 + 245 + 200 (5 times 5^2) + 144 (4 times 6^2, only top and four sides visible) + 90 (5 times 3^2) + 4 (4 times 1^2) 5. **Sum the surface areas**: - Total surface area = 405 + 320 + 245 + 200 + 144 + 90 + 4 = 1408 6. **Conclusion**: - The total surface area of the tower is 1408 square units. The final answer is boxed{1408}

question:The figure shown represents a plot of land and is drawn using a scale in which 1 cm equals 1 mile. One square mile is 640 acres. Determine the size of the actual plot of land, in acres, if the land is shaped as a rectangle with given dimensions on the map of 12 cm by 8 cm.

answer:1. Calculate the area of the plot of land in cm² since the land is a rectangle: [ text{Area} = text{length} times text{width} = 12 text{ cm} times 8 text{ cm} = 96 text{ cm}^2. ] 2. Convert the area from cm² to miles² knowing that 1 cm² on the map corresponds to 1 mile² in reality (since 1 cm = 1 mile and squaring both sides gives 1 cm² = 1 mile²): [ text{Converted Area} = 96 text{ cm}^2 times 1 text{ mile}^2/text{cm}^2 = 96 text{ miles}^2. ] 3. Convert the area from miles² to acres using the conversion factor 1 mile² = 640 acres: [ text{Area in Acres} = 96 text{ miles}^2 times 640 text{ acres/mile}^2 = 61440 text{ acres}. ] Therefore, the actual size of the plot of land is (boxed{61440 text{ acres}}).

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