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OG18-数学分册
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If S is the sum of the reciprocals of the 10 consecutive integers from 21 to 30, then S is between which of the following two fractions?
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Magoosh
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The average (arithmetic mean) of five numbers is 3x + 4. If one of the numbers is 7x - 4, what is the average of the other four numbers?
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Magoosh
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If AC = BC and CD = DE then, in terms of x, the value of y isNote: Figure not drawn to scale
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Manhattan
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A certain square has sides of length x. If the length of each side is doubled, then which of the following represents the area of the resulting square, in terms of x?
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OG19-数学分册
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$$2x+2y=-4$$
$$4x+ Y= 1$$
In the system of equations above, what is the value of x?
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In the rectangular coordinate system, points (4, 0) and (-4, 0) both lie on circle C. What is the maximum possible value of the radius of C ?
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PREP07 Test 1
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An investment of d dollars at k percent simple annual interest yields $600 interest over a 2-year period. In terms of d, what dollar amount invested at the same rate will yield $2,400 interest over a 3-year period?
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PREP07 Test 2
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A certain class, consisting of a lecture and a question-and-answer session, lasted from 2:45 to 4:30 one afternoon. If the lecture lasted from 2:45 to 4:15, then the question-and-answer session was what fraction of the total class time?
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OG21 OG2022
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Last year Brand X shoes were sold by dealers in 403 different regions worldwide, with an average （arithmetic mean） of 98 dealers per region. If last year these dealers sold an average of 2,488 pairs of Brand X shoes per dealer, which of the following is closest to the total number of pairs of Brand X shoes sold last year by the dealers worldwide?
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190603
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Mary has two methods to depart from A to C. The first one is A-B-C with speed of 80 meters per hour, and the other one is A-C with speed of 60 meters per hour. How many hours Mary used in A-C less than used in A-B-C?
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181215
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$$S_1$$=1,$$S_2$$=2,$$S_3$$=$$2^{1}$$=2,$$S_n$$={$$S_{n-1}$$}^{$$S_{n-1}$$}.$$\frac{S_6}{S_5}$$=?
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190124
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In sector AOB, ∠O=45°. The radius of the sector is 4. BC is perpendicular to OA. What is the area of the shadow?
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190310
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Eight apples and three peaches cost twice as much as three apples and four peaches. What is the ratio of the price of a peach to that of an apple?
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190603
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In the following figure, the coordinates of the points in the rectangle are expressed as (x, y). So what is the probability that x+y is less than or equal to 4?
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200301
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The sequence $$a_1$$,$$a_2$$......$$a_n$$, such that $$a_1=3$$,$$a_2 = 5$$,$$a_3 = a_1 +a_2$$,$$a_4 = a_1+a_2+a_3$$,$$a_n=a_1+a_2+$$...+$$a_{n-1}$$. What is the ratio of $$a_{24}$$ to $$a_{20}$$?
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191222
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If two dice are flipped at the same time, what is the probability that “6” shows up at least once ?
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190215
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xy is the square of an integer. Is x the square of an integer?
1: $$y^{\frac{1}{4}}$$ is an integer.
2: $$(xy)^{\frac{1}{4}}$$ is an integer.
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190215
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What is the reminder of x when divided by 2?
1: The reminder of (x+1) is odd when divided by 2.
2: 4 is a factor of $$x^{4}$$.
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OG18-数学分册
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Stephan has $$2\frac{1}{4} $$ cups of milk on hand and makes 2 batches of cookies, using $$\frac{2}{3}$$ cup of milk for each batch of cookies. Which of the following describes the amount of milk remaining after she makes the cookies?
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If $${b}\neq{0}$$, does a equal b ?1. $${{a}^{{2}^{2}}\over{b}}+{4}={5}$$2. $${{17}{a}+{4}{b}\over{7}}={3}{a}$$
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