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<span class='text_page_counter'>(1)</span>PHÒNG GIÁO DỤC VÀ ĐÀO TẠO THỊ XÃ HƯƠNG THỦY. KỲ THI GIAO LƯU HỌC SINH GIỎI TIỂU HỌC. ĐỀ THI MÔN TOÁN Thời gian làm bài : 70 phút (Không tính thời gian giao đề) Ngày 05 tháng 01 năm 2013. Họ, tên thí sinh:…………………………………………………Số báo danh:………………. Giám thị 1. Điểm :. Giám thị 2. Giám khảo 1. Mã phách : Mã phách. Giám khảo 2. I. PHẦN TRẮC NGHIỆM : (10 điểm) Khoanh vào chữ cái trước câu trả lời đúng : 4 5 Câu 1 : 15 số thứ nhất bằng 13 số thứ hai. Tỷ số của số thứ hai và số thứ nhất là : 52 13 5 75 A. 75 B. 15 C. 15 D. 52. Câu 2 : Hiệu của hai số là 3,58. Nếu số trừ gấp lên 3 lần thì được số mới lớn hơn số bị trừ là 7,2. Hai số đó là : A. 2,4 và 5,98 B. 7,2 và 10,78 C. 5,39 và 8,97 D. 3,01 và 6,59 Câu 3 : Bài kiểm tra định kì môn Toán học học kì I của lớp 5A có số học sinh đạt điểm giỏi; số học sinh đạt điểm khá, còn lại là học sinh đạt điểm trung bình. Phân số chỉ số học sinh đạt điểm trung bình của lớp 5A là : A.. 2 3. B.. 3 5. C.. 12 15. D.. 4 15. Câu 4 : Nếu giảm số đo chiều dài của một hình chữ nhật 50% thì phải tăng chiều rộng bao nhiêu phần trăm số đo của nó để diện tích hình chữ nhật đó không thay đổi? A. 200% B. 100% C. 175% D. 150% 3 Câu 5 : Một hình chữ nhật có diện tích 93,75 cm , chiều rộng bằng 5 chiều dài. Chu vi 2. hình chữ nhật đó là: A. 20cm B. 30cm C. 40cm D. 122cm Câu 6 : Số dư của phép chia 26 và 4,7 là bao nhiêu nếu chỉ lấy đến hai chữ số ở phần thập phân của thương ? A. 9 B. 0,9 C. 0,09 D. 0,009 Câu 7 : Tổng của 2 số chẵn liên tiếp là 74, hai số đó là: A. 36 và 38 B. 35 và 37 C. 34 và 40 D. 2 và 72 Câu 8 : Tổng của hai số tự nhiên là 573 và giữa chúng có 99 số chẵn khác. Hai số tự nhiên đó là : A. 237 và 336 B. 187 và 386 C. 286 và 287 D. 185 và 388.

<span class='text_page_counter'>(2)</span> . Câu 9 : Tìm một số thập phân biết rằng nếu chuyển dấu phẩy của số thập phân đó sang trái một hàng ta được số thập phân mới bé hơn số thập phân phải tìm là 2,79 đơn vị. A. 12,79 B. 3.79 C. 0,31 D. 3,1 Câu 10 : Thương của 2 số gấp lên bao nhiêu lần nếu gấp số bị chia lên 3 lần và giảm số chia 4 lần: A. 7 lần B. 12 lần C. 3 lần D. 4 lần. II. PHẦN TỰ LUẬN : (10 điểm) Bài 1 : (2 điểm) Tìm giá trị của biểu thức sau : 1 1 1 3 1 25 1 1 45 ( +0 , 25+ )+( + + + )+(0 ,75+ +50 % + +0 , 55+ ) 2 4 8 2 8 100 2 4 100 1× 2× 3. Bài 2 : (2 điểm) Trung bình cộng của 3 phân số bằng . Nếu tăng phân số thứ nhất lên 2 lần thì trung bình cộng bằng . Nếu tăng phân số thứ hai lên 2 lần thì trung bình cộng bằng . Tìm ba phân số đó. Bài 3 : (3 điểm) Ba bạn Tân, Bình, Long chung nhau mua một quyển sách. Tân góp Bình góp. 3 7. 1 3. số tiền,. số tiền. Long góp ít hơn Bình 4000 đồng. Hỏi :. a) Quyển sách giá bao nhiêu đồng ? b) Mỗi bạn góp bao nhiêu đồng ? Bài 4 : (3 điểm). A. Cho hình tam giác ABC (như hình vẽ). a) Hãy vẽ chiều cao của tam giác ABC có đỉnh A và đáy BC. b) Kéo dài BC về phía C một đoạn CD = 4,2cm. Nối AD. B. C. ta được tam giác ADC có diện tích 16,38cm 2. Tính diện tích tam giác ABC, biết cạnh BC = 5,6cm..

<span class='text_page_counter'>(3)</span> c) Tìm tỉ số phần trăm diện tích tam giác ACD và diện tích tam giác ABC. 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<span class='text_page_counter'>(10)</span> ................................................................................................................................................................................................................................................... ................................................................................................................................................................................................................................................... ................................................................................................................................................................................................................................................... ................................................................................................................................................................................................................................................... ................................................................................................................................................................................................................................................... ................................................................................................................................................................................................................................................... ................................................................................................................................................................................................................................................... ................................................................................................................................................................................................................................................... ................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................... KỲ THI GIAO LƯU HỌC SINH GIỎI Khoá ngày 05 tháng 01 năm 2013. PHÒNG GIÁO DỤC VÀ ĐÀO TẠO THỊ XÃ HƯƠNG THỦY. ĐÁP ÁN MÔN TOÁN I. Câu Phương án đúng. PHẦN TRẮC NGHIỆM (10 điểm) Đúng mỗi bài cho 1 điểm 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. A. C. D. B. C. D. A. B. D. B. II. PHẦN TỰ LUẬN (10 điểm) Câu 1 : (2 điểm).

<span class='text_page_counter'>(11)</span> 1 1 1 3 1 25 1 1 45 ( +0 , 25+ )+( + + + )+(0 ,75+ +50 % + +0 , 55+ ) 2 4 8 2 8 100 2 4 100 1× 2× 3 1 1 1 1 3 1 1 3 1 1 1 ( + + )+( + + + )+( + + + +1) 2 4 4 8 2 8 4 4 2 2 4 ¿ 1 ×2 ×3 1+2+3 6 ¿ = =1 1 ×2 ×3 6. Câu 2 : (2 điểm) Trung bình cộng của 3 phân số bằng . Nếu tăng phân số thứ nhất lên 2 lần thì trung bình cộng bằng . Nếu tăng phân số thứ hai lên 2 lần thì trung bình cộng bằng . Tìm ba phân số đó. Bài giải : Tổng của ba phân số đã cho là :. 7 7 ×3= 6 2. Tổng của ba phân số đã cho và phân số thứ nhất là :. 41 41 ×3= 30 10. điểm). Phân số thứ nhất là :. Phân số thứ hai là : Phân số thứ ba là :. (0,5 điểm). 41 7 3 − = 10 2 5. (0,25 điểm). Tổng của ba phân số đã cho và phân số thứ hai là : điểm). (0,25. 13 13 ×3= 9 3. 13 7 5 − = 3 2 6 7 3 5 62 31 − + = = 2 5 6 30 15. (0,25 điểm). ( ). Đáp số :. (0,25. (0,5 điểm) 3 ; 5. 5 31 ; 6 15. Câu 3 : (3 điểm) Ba bạn Tân, Bình, Long chung nhau mua một quyển sách. Tân góp Bình góp. 3 7. 1 3. số tiền,. số tiền. Long góp ít hơn Bình 4000 đồng. Hỏi :. c) Quyển sách giá bao nhiêu đồng ? d) Mỗi bạn góp bao nhiêu đồng ? Bài giải : Số tiền Tân và Bình góp là :. 1 3 16 + = 3 7 21. (số tiền). (0,5. điểm) Phân số chỉ số tiền Long góp là : 1− Phân số chỉ số tiền 4000 đồng là :. 16 5 = 21 21. 3 5 4 − = 7 21 21. (số tiền) (số tiền). (0,5 điểm) (0,5 điểm).

<span class='text_page_counter'>(12)</span> 4000 :. Số tiền mua quyển sách là :. 4 =21000 (đồng) 21. (0,5 điểm). 1 3. Số tiền Tân góp là : 21000 × =7000 (đồng). (0,25 điểm). 3 7. Số tiền Bình góp là : 21000 × =9000 (đồng) Số tiền Long góp là : 21000 ×. 5 =5000 21. (0,25 điểm). (đồng). (0,25 điểm). Đáp số : a) 21000 đồng b) 7000 đồng; 9000 đồng; 5000 đồng (0,25 điểm) A. Bài 4 : (3 điểm) Cho hình tam giác ABC (như hình vẽ). C. B. a) Hãy vẽ chiều cao của tam giác ABC có đỉnh A và đáy BC. b) Kéo dài BC về phía C một đoạn CD = 4,2cm. Nối AD. ta được tam giác ADC có diện tích 16,38cm 2. Tính diện tích tam giác ABC, biết cạnh BC = 5,6cm. c) Tìm tỉ số phần trăm diện tích tam giác ACD và diện tích tam giác ABC. Bài giải : a) Vẽ được chiều cao AH. (0,5 điểm). b) Vẽ được hình. (0,5 điểm). Chiều cao AH là : 16,38 x 2 : 4,2 = 7,8 (cm). A. (0,5 điểm). AH là chiều cao của tam giác ABC và cũng là chiều cao của tam giác ADC Diện tich tam giác ABC là : 5,6 x 7,8 : 2 = 21,84 (cm2). 16,38cm2. (0,25 điểm) H. (0,5 điểm). c) Tỷ số phần trăm diện tích tam giác ADC và diện tíc tam giác ABC là : 16,38 : 21,84 = 0,75 = 75%. (0,75 điểm). Học sinh giải bằng cách khác đúng vẫn cho điểm tối đa. B. C 4,2cm. D.

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