1. Ben has 20 coins which consist only of $2 coins and $5 coins.If the total amount of these coins is not less than $85 ,how many $ 2 coins can he have at most?
2. The sum of the weights of Miss Wong and Mr Ho is not greater than 124kg . If the weight of Mr Ho is 1.5 times the weight of Miss Wong , find the maximun possible weight of Mr Ho .
( please write in detail )
F.2 maths
2008-03-07 3:51 am
回答 (2)
2008-03-07 4:08 am
✔ 最佳答案
1. Let the no. of $2 coins be x2x+5(20-x) ≥ 85
2x+100-5x ≥ 85
15 ≥ 3x
x ≤ 5
Therefore, he can have five $2 coins at most.
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2. Let the weight of Mr. Ho be x kg
x + x/1.5 ≤ 124
1.5x + x ≤ 186
2.5x ≤ 186
x ≤ 74.4
Therefore, the maximun possible weight of Mr. Ho is 74.4 kg
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參考: me
2008-03-07 4:03 am
let x be the number of $2 coins.
2x+5(20-x)>=85
2x+100-5x>=85
-3x>=-15
3x<=15
x<=15
ans: at most 15 $2 coins.
let x be the weight of Mr Ho.
x+2/3x <=124
5/3x<=124
x<=124/5*3
x<=74.4
ans: maximum possible weight of Mr Ho is 74.4kg
2x+5(20-x)>=85
2x+100-5x>=85
-3x>=-15
3x<=15
x<=15
ans: at most 15 $2 coins.
let x be the weight of Mr Ho.
x+2/3x <=124
5/3x<=124
x<=124/5*3
x<=74.4
ans: maximum possible weight of Mr Ho is 74.4kg
收錄日期: 2021-04-19 00:37:56
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