Đề thi học sinh giỏi Toán Lớp 5 - Năm học 2008-2009 - Trường Tiểu học Ngọc Sơn

Tê giÊy thi
M«n : To¸n - Líp 5 - N¨m häc : 2008 – 2009
Thêi gian: 90 phót
 §iÓm bµi thi Hä tªn ch÷ kÝ ng­êi chÊm Sè ph¸ch
B»ng sè B»ng ch÷ 1/: .............................................................
............ ....................... 2/ : .............................................................
Bài 1: a/ Viết các phân số sau đây dưới dạng số thập phân.
 =  ; = ..
b/ Viết các số thập phân sau đây dưới dạng phân số: 
0,75 = ............. = ............. ; 2,5 = ............. = ...............
Bµi 2 : Cho biÓu thøc : A = 4,25 ( a + 41,53 ) – 125
a/ TÝnh gi¸ trÞ cña biÓu thøc A khi a = 58,74.
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b/ T×m gi¸ trÞ cña a ®Ó A = 53,5
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Bµi 3 : Cho ph©n sè cã : a + b = 7525 vµ a - b = 903. H·y x¸c ®Þnh ph©n sè ®ã råi rót gän.
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Bµi 4 : Mét ng­êi b¸n v¶i, lÇn thø nhÊt b¸n tÊm v¶i; lÇn thø hai b¸n tÊm v¶i cßn l¹i. Sau hai lÇn b¸n, tÊm v¶i cßn l¹i 24 m. Hái lóc ®Çu tÊm v¶i dµi bao nhiªu m ?
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Bµi 5 : Tam gi¸c ABC cã diÖn tÝch lµ 120 cm2, D lµ ®iÓm chÝnh gi÷a cña c¹nh AB. Trªn c¹nh AC, lÊy ®iÓm I sao cho AI = AC. TÝnh diÖn tÝch tam gi¸c DAI.
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Bµi 6 : TÝnh nhanh:
	y 8,01 – y : 100 = 38
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