2022 澳洲 AMC C-Junior 真题 答案 详解

中英双语真题

2022 AMC Junior Questions 15 Junior Questions 1. What is the perimeter of this rhombus? (A) 20 cm (B) 24 cm (C) 28 cm (D) 32 cm (E) 36 cm 9 cm 9 cm 2. The temperature in the mountains was 4°C but dropped overnight by 7°C. What was the temperature in the morning? (A) 3°C (B) 11°C (C) -3°C (D) -4°C (E) -11°C 3. What is the value of 20 × 22? (A) 42 (B) 440 (C) 2022 (D) 2220 (E) 4400 4. Which spinner is twice as likely to land on red as white? (A) (B) (C) (D) (E) 5. Russell's tuba lesson started at 4:28 pm and finished at 5:05 pm. How long was the lesson? (A) 23 minutes (B) 27 minutes (C) 33 minutes (D) 37 minutes (E) 43 minutes 6. What fraction of the square is shaded? (A) ( \frac{1}{3} ) (B) ( \frac{1}{4} ) (C) ( \frac{2}{5} ) (D) ( \frac{1}{2} ) (E) ( \frac{3}{8} ) 7. What is the value of (10^3 - 11^2)? (A) 8 (B) 22 (C) 279 (D) 779 (E) 879 8. Which one of these fractions lies between 4 and 5 on the number line? (A) ( \frac{7}{2} ) (B) ( \frac{15}{4} ) (C) ( \frac{16}{5} ) (D) ( \frac{17}{4} ) (E) ( \frac{18}{5} ) www.amt.edu.au

英文真题

2022 AMC Junior Questions 15 Junior Questions 1. What is the perimeter of this rhombus? (A) 20 cm (B) 24 cm (C) 28 cm (D) 32 cm (E) 36 cm 9 cm 9 cm 2. The temperature in the mountains was 4°C but dropped overnight by 7°C. What was the temperature in the morning? (A) 3°C (B) 11°C (C) -3°C (D) -4°C (E) -11°C 3. What is the value of 20 × 22? (A) 42 (B) 440 (C) 2022 (D) 2220 (E) 4400 4. Which spinner is twice as likely to land on red as white? (A) (B) (C) (D) (E) 5. Russell's tuba lesson started at 4:28 pm and finished at 5:05 pm. How long was the lesson? (A) 23 minutes (B) 27 minutes (C) 33 minutes (D) 37 minutes (E) 43 minutes 6. What fraction of the square is shaded? (A) 1/3 (B) 1/4 (C) 2/5 (D) 1/2 (E) 3/8 2 2 2 1 7. What is the value of 10³ - 11²? (A) 8 (B) 22 (C) 279 (D) 779 (E) 879 8. Which one of these fractions lies between 4 and 5 on the number line? (A) 7/2 (B) 15/4 (C) 16/5 (D) 17/4 (E) 18/5 www.amt.edu.au

真题文字详解(英文)

46 2022 AMC Junior Solutions Junior Solutions 1. The rhombus has 4 sides, each of length 9 cm, so the perimeter is 4 × 9 = 36 cm, hence (E). 2. (Also S1) 4 - 7 = -3, hence (C). 3. 20 × 22 = 440, hence (B). 4. (Also UP11) We look for the spinner which has twice as many red sections as white sections. The fourth spinner has 4 red sections and 2 white sections and is the only one which fits, hence (D). 5. From 4:28 pm to 5 pm is 32 minutes and from 5 pm to 5:05 pm is 5 minutes. So Russell's tuba lesson is 32 + 5 = 37 minutes long, hence (D). 6. Alternative 1 The square has area 2 × 2 = 4. The shaded triangle has area \frac{1}{2} × 1 × 2 = 1. Therefore the shaded triangle is \frac{1}{4} of the area, hence (B). Alternative 2 The square can be divided into 4 copies of the shaded triangle, so the shaded triangle is \frac{1}{4} of the area, hence (B). 7. 10^3 - 11^2 = 1000 - 121 = 879, hence (E). 8. Alternative 1 Converting to mixed numbers, \frac{7}{2} = 3\frac{1}{2}, \frac{15}{4} = 3\frac{3}{4}, \frac{16}{5} = 3\frac{1}{5}, \frac{17}{4} = 4\frac{1}{4}, and \frac{18}{5} = 3\frac{3}{5}. Of these, only 4\frac{1}{4} is between 4 and 5, hence (D). www.amt.edu.au