2018 AMC12B 真题

2018 AMC 12B

Problem 1

Kate bakes a -inch by -inch pan of cornbread. The cornbread is cut into pieces that measure inches by inches. How many pieces of cornbread does the pan contain?

Kate 烤了一块 20 英寸乘以 18 英寸的玉米面包，这块玉米面包被切分成 2 英寸乘以 2 英寸的 多个小块面包。问这大块玉米面包包含多少块小块面包？

(A) 90 (B) 100 (C) 180 (D) 200 (E) 360

Problem 2

Sam drove miles in minutes. His average speed during the first minutes was mph (miles per hour), and his average speed during the second minutes was mph. What was his average speed, in mph, during the last minutes?

Sam 在 90 分钟内开了 96 英里。他在前 30 分钟内的平均速度为 60 英里每小时，在第二个 30 分钟内的平均速度为 65 英里每小时。他在最后 30 分钟内的平均速度是多少英里每小时？

(A) 64 (B) 65 (C) 66 (D) 67 (E) 68

Problem 3

A line with slope intersects a line with slope at the point . What is the distance between the -intercepts of these two lines?

一条斜率为 的直线和一条斜率为 2 6 的直线交于点（ 40 ， 30 ）。那么这 2 条直线的 截距的 x 距离是多少？

(A) 5 (B) 10 (C) 20 (D) 25 (E) 50

Problem 4

A circle has a chord of length , and the distance from the center of the circle to the chord is . What is the area of the circle?

(C) 75T (E) 1257

一个圆的一条弦长为 10 ，圆心到弦的距离是 ，那么这个圆的面积是多少？ 5