1998 AMC8 #2 · Algebra ·
If (abcd)=adbc\begin{pmatrix} a & b \\ c & d \end{pmatrix} = ad - bc, then (2113)+(3214)=\begin{pmatrix} 2 & 1 \\ 1 & 3 \end{pmatrix} + \begin{pmatrix} 3 & 2 \\ 1 & 4 \end{pmatrix} =
(abcd)=adbc\begin{pmatrix} a & b \\ c & d \end{pmatrix} = ad - bc,则 (2113)+(3214)=\begin{pmatrix} 2 & 1 \\ 1 & 3 \end{pmatrix} + \begin{pmatrix} 3 & 2 \\ 1 & 4 \end{pmatrix} =

正确答案:E · 分值:1

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1998 AMC8 #4 · Geometry · ★★
How many triangles are in this figure? (Some triangles may overlap other triangles.)
图中有多少个三角形?(有些三角形可能与其他三角形重叠。)

正确答案:E · 分值:1

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1998 AMC8 #6 · Geometry · ★★
Dots are spaced one unit apart, horizontally and vertically. The number of square units enclosed by the polygon is
点之间水平和垂直方向间距均为一个单位。该多边形围成的面积是多少平方单位?

正确答案:B · 分值:1

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1998 AMC8 #8 · Algebra ·
A child's wading pool contains 200 gallons of water. If water evaporates at the rate of 0.5 gallons per day and no other water is added or removed, how many gallons of water will be in the pool after 30 days?
一个儿童戏水池装有 200 加仑水。如果水以每天 0.5 加仑的速度蒸发,且没有其他水的添加或移除,30 天后池中还有多少加仑水?

正确答案:C · 分值:1

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1998 AMC8 #9 · Algebra · ★★
For a sale, a store owner reduces the price of a $10 scarf by 20% . Later the price is lowered again, this time by one-half the reduced price. The price is now
为了促销,一家商店的老板将一条 $10 的围巾降价 20%。之后价格再次下调,这次是下调后价格的一半。现在的价格是

正确答案:C · 分值:1

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1998 AMC8 #10 · Number Theory · ★★
Each of the letters W\text{W} , X\text{X} , Y\text{Y} , and Z\text{Z} represents a different integer in the set {1,2,3,4}\{ 1,2,3,4\} , but not necessarily in that order. If WXYZ=1\dfrac{\text{W}}{\text{X}} - \dfrac{\text{Y}}{\text{Z}}=1 , then the sum of W\text{W} and Y\text{Y} is
字母 W\text{W}X\text{X}Y\text{Y}Z\text{Z} 各代表集合 {1,2,3,4}\{1,2,3,4\} 中不同的整数,但不一定按此顺序。若 WXYZ=1\dfrac{\text{W}}{\text{X}} - \dfrac{\text{Y}}{\text{Z}}=1,则 W\text{W}Y\text{Y} 之和为

正确答案:E · 分值:1

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1998 AMC8 #11 · Counting, Probability & Statistics · ★★★
Harry has 3 sisters and 5 brothers. His sister Harriet has S\text{S} sisters and B\text{B} brothers. What is the product of S\text{S} and B\text{B} ?
Harry 有 3 个姐妹和 5 个兄弟。他的姐妹 Harriet 有 S\text{S} 个姐妹和 B\text{B} 个兄弟。S\text{S}B\text{B} 的乘积是多少?

正确答案:C · 分值:1

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1998 AMC8 #13 · Geometry · ★★★
What is the ratio of the area of the shaded square to the area of the large square? (The figure is drawn to scale)
着色正方形的面积与大正方形的面积之比是多少?(图形按比例绘制)

正确答案:C · 分值:1

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1998 AMC8 #14 · Algebra · ★★★
An Annville Junior High School, 30% of the students in the Math Club are in the Science Club, and 80% of the students in the Science Club are in the Math Club. There are 15 students in the Science Club. How many students are in the Math Club?
在 Annville 初中,数学俱乐部中 30% 的学生也在科学俱乐部,科学俱乐部中 80% 的学生也在数学俱乐部。科学俱乐部有 15 名学生。数学俱乐部有多少名学生?

正确答案:E · 分值:1

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1998 AMC8 #15 · Algebra · ★★★
Estimate the population of Nisos in the year 2050.
在 Irenic 海的中央坐落着美丽的 Nisos 群岛。1998 年这些岛屿上的人口仅为 200,但人口每 25 年翻三倍。Irene 女王已颁布法令,岛上每个人必须有至少 1.5 平方英里的空间。Nisos 群岛的总面积为 24,900 平方英里。
估计 2050 年 Nisos 的人口。

正确答案:D · 分值:1

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1998 AMC8 #16 · Algebra · ★★★
Estimate the year in which the population of Nisos will be approximately 6,000.
在 Irenic 海的中央坐落着美丽的 Nisos 群岛。1998 年这些岛屿上的人口仅为 200,但人口每 25 年翻三倍。Irene 女王已颁布法令,岛上每个人必须有至少 1.5 平方英里的空间。Nisos 群岛的总面积为 24,900 平方英里。
估计 Nisos 人口大约达到 6,000 的年份。

正确答案:B · 分值:1

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1998 AMC8 #17 · Algebra · ★★★
In how many years, approximately, from 1998 will the population of Nisos be as much as Queen Irene has proclaimed that the islands can support?
在 Irenic 海的中央坐落着美丽的 Nisos 群岛。1998 年这些岛屿上的人口仅为 200,但人口每 25 年翻三倍。Irene 女王已颁布法令,岛上每个人必须有至少 1.5 平方英里的空间。Nisos 群岛的总面积为 24,900 平方英里。
大约从 1998 年起多少年后,Nisos 的人口会达到 Irene 女王宣布的群岛可承载的数量?

正确答案:C · 分值:1

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1998 AMC8 #18 · Geometry · ★★★
As indicated by the diagram below, a rectangular piece of paper is folded bottom to top, then left to right, and finally, a hole is punched at X. What does the paper look like when unfolded?
如下图所示,将一张矩形纸从下往上折叠,再从左往右折叠,最后在 X 处打一个孔。展开后纸张是什么样子?

正确答案:B · 分值:1

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1998 AMC8 #19 · Counting, Probability & Statistics · ★★★
Tamika selects two different numbers at random from the set {8,9,10}\{ 8,9,10 \} and adds them. Carlos takes two different numbers at random from the set {3,5,6}\{3, 5, 6\} and multiplies them. What is the probability that Tamika's result is greater than Carlos' result?
Tamika 从集合 {8,9,10}\{8,9,10\} 中随机选两个不同的数并相加。Carlos 从集合 {3,5,6}\{3,5,6\} 中随机选两个不同的数并相乘。Tamika 的结果大于 Carlos 的结果的概率是多少?

正确答案:A · 分值:1

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1998 AMC8 #20 · Geometry · ★★★
Let PQRSPQRS be a square piece of paper. PP is folded onto RR and then QQ is folded onto SS . The area of the resulting figure is 9 square inches. Find the perimeter of square PQRSPQRS .
PQRSPQRS 为一张正方形纸。将 PP 折到 RR 上,再将 QQ 折到 SS 上。所得图形的面积为 9 平方英寸。求正方形 PQRSPQRS 的周长。

正确答案:D · 分值:1

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1998 AMC8 #21 · Geometry · ★★★
AA4×4×44\times 4\times 4 cubical box contains 64 identical small cubes that exactly fill the box. How many of these small cubes touch a side or the bottom of the box?
一个 4×4×44\times 4\times 4 的正方体盒子内装有 64 个完全相同的小正方体,恰好填满盒子。这些小正方体中有多少个接触盒子的侧面或底面?

正确答案:B · 分值:1

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1998 AMC8 #22 · Number Theory · ★★★★
Terri produces a sequence of positive integers by following three rules. She starts with a positive integer, then applies the appropriate rule to the result, and continues in this fashion. Rule 1: If the integer is less than 10, multiply it by 9. Rule 2: If the integer is even and greater than 9, divide it by 2. Rule 3: If the integer is odd and greater than 9, subtract 5 from it. A sample sequence: 23,18,9,81,76,.23, 18, 9, 81, 76, \ldots . Find the 98th98^\text{th} term of the sequence that begins 98,49,.98, 49, \ldots .
Terri 按照以下三条规则生成一个正整数序列。她从一个正整数开始,然后对结果应用适当的规则,并继续以此方式进行。
规则 1:如果整数小于 10,乘以 9。 规则 2:如果整数为偶数且大于 9,除以 2。 规则 3:如果整数为奇数且大于 9,减去 5。
示例序列:23,18,9,81,76,23, 18, 9, 81, 76, \ldots
求以 98,49,98, 49, \ldots 开头的序列的第 98 项。

正确答案:D · 分值:1

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1998 AMC8 #23 · Algebra · ★★★★
If the pattern in the diagram continues, what fraction of eighth triangle would be shaded?
如果图中的图案继续下去,第八个三角形着色部分的比例是多少?

正确答案:C · 分值:1

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1998 AMC8 #24 · Number Theory · ★★★★
A rectangular board of 8 columns has squares numbered beginning in the upper left corner and moving left to right so row one is numbered 1 through 8, row two is 9 through 16, and so on. A student shades square 1, then skips one square and shades square 3, skips two squares and shades square 6, skips 3 squares and shades square 10, and continues in this way until there is at least one shaded square in each column. What is the number of the shaded square that first achieves this result?
一块有 8 列的矩形板,方格从左上角开始从左到右编号,第一行为 1 到 8,第二行为 9 到 16,以此类推。一个学生涂黑了方格 1,然后跳过一个方格涂黑方格 3,跳过两个方格涂黑方格 6,跳过 3 个方格涂黑方格 10,并继续按此方式操作,直到每一列至少有一个涂黑的方格。首次达到此结果时涂黑的方格编号是多少?

正确答案:E · 分值:1

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1998 AMC8 #25 · Algebra · ★★★★
Three generous friends, each with some money, redistribute the money as followed: Amy gives enough money to Jan and Toy to double each of their amounts. Jan then gives enough to Amy and Toy to double their amounts. Finally, Toy gives enough to Amy and Jan to double their amounts. If Toy had 36 dollars at the beginning and 36 dollars at the end, what is the total amount that all three friends have?
三位慷慨的朋友各自拥有一些钱,按如下方式重新分配:Amy 给 Jan 和 Toy 足够的钱,使他们各自的金额翻倍。然后 Jan 给 Amy 和 Toy 足够的钱,使他们的金额翻倍。最后,Toy 给 Amy 和 Jan 足够的钱,使他们的金额翻倍。如果 Toy 一开始有 36 美元,最后也有 36 美元,那么三位朋友共有多少钱?

正确答案:D · 分值:1

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