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题目： Machine A, working alone at a constant rate, can complete a certain production lot in x hours. Machine B, working alone at a constant rate, can complete 1/5 of the same production lot in y hours. Machines A and B, working together, can complete$$ \frac{1}{2}$$ of the same production lot in z hours. What is the value of y in terms of x and z?

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题目： $$10 ^{5} – 560 $$ is divisible by all of the following EXCEPT:

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题目： Which of the following is greater than $$\frac{3}{4} $$?

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题目： The longevity of a certain metal construction is determined by the following formula: $$l = {(7.5 – x)}^{4} + 8.97^{c}$$, where l is the longevity of the construction, in years, x is the density of the underlying material, in $$\frac{g}{cm^{3}}$$, and c is a positive constant equal to 1.05 for this type of metal constructions. For what value of density, x, expressed in $$\frac{g}{cm^{3}}$$, will the metal construction have minimal longevity?

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题目： Line A is drawn on a rectangular coordinate plane. If the coordinate pairs (3, 2) and (-1, -2) lie on line A, which of the following coordinate pairs does NOT lie on a line that is perpendicular to line A?

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题目： The manufacturer's suggested retail price (MSRP) of a certain item is $60. Store A sells the item for 20 percent more than the MSRP. The regular price of the item at Store B is 30 percent more than the MSRP, but the item is currently on sale for 10 percent less than the regular price. If sales tax is 5 percent of the purchase price at both stores, how much more will someone pay in sales tax to purchase the item at Store A?

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题目： Set S consists of integers 7, 8, 10, 12, and 13. If integer n is included in the set, the average (arithmetic mean) of set S will increase by 20%. What is the value of integer n?

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题目： If r and p are two different prime numbers, which of the following is the smallest possible value of r + p?

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题目： S and T are two-digit positive integers that have the same digits but in reverse order. If the positive difference between S and T is less than 40, what is the greatest possible value of S minus T?

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题目： How many of the integers between 40 and 100, inclusive, are even?

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题目： Line segments AB and CD are of equal length and perpendicular bisectors of one another. If a line segment is drawn connecting point A to point C, what is the measure of angle ACD?

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题目： If |a| = |b|, which of the following must be true? I. a = b II. |a| = -b III. -a = -b

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题目： Which of the following would result in a remainder of 7 when divided by 12? I. 151 II. 3,443 III. 5,995

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题目： If the price of a certain stock increased by $$\frac{1}{5}$$ during the first month and then decreased by $$\frac{1}{4}$$ during the second month, what was the ratio of the stock price at the end of the two months to the original price?

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题目： Jolene entered an 18-month investment contract that guarantees to pay 2 percent interest at the end of 6 months, another 3 percent interest at the end of 12 months, and 4 percent interest at the end of the 18 month contract. If each interest payment is reinvested in the contract, and Jolene invested $10,000 initially, what will be the total amount of interest paid during the 18-month contract?