2019 澳洲 AMC C-Junior 真题 答案 详解

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中英双语真题

1. 201 - 9 =
   201 - 9 =
   (A) 111 (B) 182 (C) 188 (D) 192 (E) 198

2. This rectangle is 5 cm wide and 4 cm tall. What is its area in square centimetres?
   (A) 9 (B) 10 (C) 18 (D) 20 (E) 40

3. The table shows the number of boys and girls aged 10 or 11 in year 5. How many boys aged 11 are in year 5?
   (A) 9 (B) 11 (C) 21 (D) 37 (E) 46

4. The circles are in a regular rectangular pattern. Some circles are hidden by the card. What fraction of the circles is hidden?
   (A) ( \frac{1}{3} ) (B) ( \frac{2}{3} ) (C) ( \frac{1}{4} ) (D) ( \frac{1}{6} ) (E) ( \frac{1}{18} )

英文真题

Junior Division
Questions 1 to 10, 3 marks each

1. (201 - 9 =)
   (A) 111
   (B) 182
   (C) 188
   (D) 192
   (E) 198

2. This rectangle is 5 cm wide and 4 cm tall. What is its area in square centimetres?
   (A) 9
   (B) 10
   (C) 18
   (D) 20
   (E) 40

3. The table shows the number of boys and girls aged 10 or 11 in year 5. How many boys aged 11 are in year 5?
   | | Age 10 | Age 11 | Total | |--------|--------|--------|-------| | Girls | 14 | 25 | 39 | | Boys | 9 | ? | 46 | | Total | 23 | 62 | 85 |

(A) 9
(B) 11
(C) 21
(D) 37
(E) 46

1. The circles are in a regular rectangular pattern. Some circles are hidden by the card. What fraction of the circles is hidden?
   (A) (\frac{1}{3})
   (B) (\frac{2}{3})
   (C) (\frac{1}{4})
   (D) (\frac{1}{6})
   (E) (\frac{1}{18})

2. Which one of the following is the largest number?
   (A) 4.05
   (B) 4.45
   (C) 4.5
   (D) 4.045
   (E) 4.54

3. What is 25% of (\frac{1}{2})?
   (A) (\frac{1}{16})
   (B) (\frac{1}{8})
   (C) (\frac{1}{4})
   (D) 1
   (E) 2

真题文字详解(英文)

2019 AMC Junior Solutions 1. (Also UP1) 201 - 9 = 192, hence (D). 2. The rectangle's area is 4 cm × 5 cm = 20 cm², hence (D). 3. The number of boys is 46, and 9 of them are 10 years old. The number of boys who are 11 years old is 46 - 9 = 37, hence (D). 4. There will be 6 circles under the card, out of 24 in total. The hidden fraction is 6/24 = 1/4, hence (C). 5. In increasing order, the numbers are 4.045, 4.05, 4.45, 4.5, 4.54, hence (E). 6. 25% = 25/100 = 1/4, so the answer is 1/4 × 1/2 = 1/8, hence (B). 7. (Also UP8) Halfway to Rennmark is 230 ÷ 2 = 115 km. Blanchetown is 9 km short of this, and Waikerie is 33 km beyond, so Blanchetown is closest to halfway, hence (D). 8. These are the transformations: F → E, hence (E). 9. In the digits column, the digit 1 appears twice, in the numbers 1 and 11. In the tens column, the digit 1 appears ten times, in the numbers 10 to 19. So in total, the digit 1 appears 12 times, hence (D). 10. 3.125 = 3 125/1000 = 3 1/8 = 25/8. Further, this is in simplest terms, since 8 and 25 have no common factor. Then P = 25, Q = 8 is the smallest solution. All larger solutions are multiples of this, so will have P > 30. So the only possible value of Q is 8, hence (C). www.amt.edu.au | 47