2012 袋鼠数学 E-Junior 真题 答案 详解

英文真题

International Kangaroo Mathematics Contest 2012 - Junior Level Junior (Class 9 & 10) Time Allowed : 3 hours SECTION ONE - (3 points problems) 1. The diagram shows an isosceles triangle; M and N are the midpoints of the equal sides. The triangle has been divided into four regions by two straight lines. Three of the regions have areas 3, 3 and 6, as shown. What is the area of the fourth region? (A) 3 (B) 4 (C) 5 (D) 6 (E) 7 2. 11.11 - 1.111 = (A) 9.009 (B) 9.0909 (C) 9.99 (D) 9.999 (E) 10 3. A cuboid is made of four pieces, as shown. Each piece consists of four cubes and is a single colour. What is the shape of the white piece? (A) (B) (C) (D) (E) 4. When Alice wants to send a message to Bob, she uses the following system, known to Bob. For each letter in the message, she converts the letter to a number, using A = 01, B = 02, C = 03, ..., Z = 26, and then calculates 2 x number +9. Alice sends the sequence of results to Bob. This morning Bob received the sequence 25 - 19 - 45 - 38. What was the original