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题目： From a group of 3 boys and 3 girls, 4 children are to be randomly selected. What is the probability that equal numbers of boys and girls will be selected?

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题目： Company S produces two kinds of stereos:basic and deluxe. Of the stereos produced by Company S last month, $$\frac2 3$$ were basic and the rest were deluxe. If it takes $$\frac7 5$$ as many hours to produce a deluxe stereo as it does to produce a basic stereo, then the number of hours it took to produce the deluxe stereos last month was what fraction of the total number of hours it took to produce all the stereos?

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题目： In the xy-plane, what is the x-intercept of the line whose equation is 3y – 4x = 15?

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题目： If a code word is defined to be a sequence of different letters chosen from the 10 letters A, B, C, D, E, F, G, H, I, and J, what is the ratio of the number of 5-letter code words to the number of 4-letter code words?

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题目： What is the probability that a student randomly selected from a class of 60 students will be a male who has brown hair?(1)One-half of the students have brown hair.(2)One-third of the students are males.

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题目： If two copying machines work simultaneously at their respective constant rates, how many copies do they produce in 5 minutes?(1)One of the machines produces copies at the constant rate of 250 copies per minute.(2)One of the machines produces copies at twice the constant rate of the other machine.

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题目： If a certain machine produces bolts at a constant rate, how many seconds will it take the machine to produce 300 bolts?(1)It takes the machine 56 seconds to produce 40 bolts.(2)It takes the machine 1.4 seconds to produce 1 bolt.

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题目： In a certain English class, $$\frac1 4$$ of the number of girls is equal to $$\frac1 6$$ of the total number of students. What is the ratio of the number of boys to the number of girls in the class?

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题目： If M is the least common multiple of 90, 196, and 300, which of the following is NOT a factor of M?

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题目： If n is a positive integer, which of the following is a possible value of |56 - 5n|?

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题目： June 25, 1982, fell on a Friday. On which day of the week did June 25, 1987, fall? (Note:1984 was a leap year.)

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题目： In the sequence 1, 2, 4, 8, 16, 32, -, each term after the first is twice the previous term. What is the sum of the 16th, 17th, and 18th terms in the sequence?

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题目： If x< 0, then $$\sqrt{-x|x|}$$ is

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题目： There are 8 books on a shelf, of which 2 are paperbacks and 6 are hardbacks. How many possible selections of 4 books from this self include at least one paperback?

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题目： Is $${h}^{2}={h}$$ ?(1) h + h = h(2) h - h = h