奥數 2 questions (15point) :
Solve it ! help!
1 : Finding the volume of a box
The area of the top of a rectangular box is 252cm2 , the area of the front of the box
is 105cm2 , and the surface area of the box is 834cm2 . What is the volume of the box ?
2 : Counting Chicken Wings
At Annie's Home-Cooked Chicken Wings Restaurant , chicken wings are served by the bucket . The Biggest Bucket O' Wings is really big! Let's figure out how many
wings are in it . If they're removed two at a time , one wing will be left .
If they're removed three at a time , two wings will remain . If they're removed four ,
five , or six at time , then three , four , and five wings , respectively , will remain .
If they're taken out seven at a time , no wings will be left over . What's the smallest possible number of wings that could be in the bucket ? Explain your answer .
maths problem15point(奥數X2)easy
2014-02-05 8:48 pm
回答 (4)
2014-02-05 9:11 pm
✔ 最佳答案
1. 748.42. (一定是單數,因為除2餘下1)不會5字尾(0 2 4 5 6 8)字尾是錯的只有1 3 7 9字尾,看7 的倍數 7,wrong 14wrong 21wrong 28 wrong 35 wrong 42 wrong ,49 wrong ....at last the answer is 119!
hope can help u
2014-02-06 11:15:24 補充：
ka ho ,the step of the first question i don't understand
2014-02-06 11:17:55 補充：
why you know the height is 5 cm?
2014-02-06 11:19:52 補充：
表面積一定比volume的數字大,沒可能是1260,是不是計錯?
2014-02-06 11:25:46 補充：
because you say lw is 252 ,mean 252x5=1260(wxlxh=volume, 252 is wxl),you mean height is 5,then long will be 12 cm because lh=60,but then mean wide is 21cm!
2014-02-14 3:39 am
1.The area of the side of the box
=(834cm^2-2*252cm^2-2*105cm^2)/2
=120cm^2/2
=60cm^2
The volume of the box
=√(252cm^2*105cm^2*60cm^2)
=1260cm^3
2. 除2餘1--the number of wings is an odd number
除5餘4--個位是4 或9
但雞翼數量是單數
所以個位一定是9
除3餘2--因為如果把各位數加起來為3的倍數這個數字就是3的倍數
所以把雞翼數量各位數加起來，這個數字一定也是欠1就能成為3的倍數
最近的數字是29
這個數字也是除4餘3以及除6餘5
Therefore,the smallest possible number of wings that could be 29 in the bucket.
2014-02-13 19:59:40 補充：
Oh,sorry
第2題我錯了.......
29除4餘1.....
=(834cm^2-2*252cm^2-2*105cm^2)/2
=120cm^2/2
=60cm^2
The volume of the box
=√(252cm^2*105cm^2*60cm^2)
=1260cm^3
2. 除2餘1--the number of wings is an odd number
除5餘4--個位是4 或9
但雞翼數量是單數
所以個位一定是9
除3餘2--因為如果把各位數加起來為3的倍數這個數字就是3的倍數
所以把雞翼數量各位數加起來，這個數字一定也是欠1就能成為3的倍數
最近的數字是29
這個數字也是除4餘3以及除6餘5
Therefore,the smallest possible number of wings that could be 29 in the bucket.
2014-02-13 19:59:40 補充：
Oh,sorry
第2題我錯了.......
29除4餘1.....
參考: me
2014-02-07 7:56 pm
表面積一定比volume的數字大〈——謬論 表面積同體積冇話邊個一定大/細過另外一個
例如，一個長12，闊11，高10嘅長方體，佢嘅表面積724，而體積就系1320
例如，一個長12，闊11，高10嘅長方體，佢嘅表面積724，而體積就系1320
2014-02-06 12:05 am
Let lw=252
wh=105
2wh+2lh+2lw=834
wh+lh+lw=417
105+lh+252=417
lh=60
Volume=lwh=sqrt[(lw)(wh)(lh)]=sqrt[60*105*252]=1260
N=2a-1=3b-1=4c-1=5d-1=6e-1 =7f
i.e. N+1 is the least common multiple of 2 , 3 , 4 , 5 , 6 for N is a multiple of 7
6=3*2 4=2*2
∴The multiple of the L.C.M of 4, 5, 6 are that of 2 , 3, 4, 5, 6
=> 60 , 120 , 180....
59/7=8.43..... (rejected)
119/7=17
i.e. 119 is the answer
wh=105
2wh+2lh+2lw=834
wh+lh+lw=417
105+lh+252=417
lh=60
Volume=lwh=sqrt[(lw)(wh)(lh)]=sqrt[60*105*252]=1260
N=2a-1=3b-1=4c-1=5d-1=6e-1 =7f
i.e. N+1 is the least common multiple of 2 , 3 , 4 , 5 , 6 for N is a multiple of 7
6=3*2 4=2*2
∴The multiple of the L.C.M of 4, 5, 6 are that of 2 , 3, 4, 5, 6
=> 60 , 120 , 180....
59/7=8.43..... (rejected)
119/7=17
i.e. 119 is the answer
收錄日期: 2021-04-13 20:00:28
原文連結 [永久失效]:
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