2020 袋鼠数学 D-Cadet 真题 答案 详解

2020 年 D-Cadet 真题,中英双语,答案,详解

英文真题

30th INTERNATIONAL KANGAROO MATHEMATICS CONTEST 2020
KSF - Problems Cadet (Class 7 & 8)
Time Allowed: 180 minutes

SECTION ONE - (3 point problems)

1. How many of the following four numbers 2, 20, 202, 2020 are prime?
   (A) 0
   (B) 1
   (C) 2
   (D) 3
   (E) 4

2. In which of the regular polygons below is the marked angle the largest?
   (A)
   (B)
   (C)
   (D)
   (E)

3. Miguel solves six Olympiad problems every day and Lázaro solves four Olympiad problems every day. How many days does it take Lázaro to solve the same number of problems as Miguel solves in four days?
   (A) 4
   (B) 5
   (C) 6
   (D) 7
   (E) 8

4. Which of these fractions has the largest value?
   (A) ( \frac{8+5}{3} )
   (B) ( \frac{8}{3+5} )
   (C) ( \frac{3+5}{8} )
   (D) ( \frac{8+3}{5} )
   (E) ( \frac{3}{8+5} )

5. A large square is divided into smaller squares. In one of the squares a diagonal is also drawn. What fraction of the large square is shaded?
   (A) ( \frac{4}{5} )
   (B) ( \frac{3}{8} )
   (C) ( \frac{4}{9} )
   (D) ( \frac{1}{3} )
   (E) ( \frac{1}{2} )