這算式應怎列算? 要算式及答案
1. If (2a+b) : (3a+4b) = 4 : 11, find a : b=
2. A bag contains three kinds of coins. Given that number of $5 coins : number of $2 coins : number of $1 coins = 4 : 3 : 2 and the total amount of the coins is $84, find the number of $5 coins.
中學數學想問
2008-03-21 9:39 pm
回答 (2)
2008-03-21 9:48 pm
✔ 最佳答案
1. (2a+b) : (3a+4b) = 4 : 1111x((2a+b) = 4 x (3a+4b)
22a + 11b =12a + 16b
10a=5b
a/b= 5/10 = 1/2
a : b = 1 : 2
2. Let a be the total number of coins.
number of $5 coins = 4a/(4+3+2) = 4a/9
number of $2 coins = 3a/(4+3+2) = 3a/9
number of $1 coins = 2a/(4+3+2) = 2a/9
5x4a/9 + 2x3a/9 + 1x2a/9 = 84
20a/9 + 6a/9 + 2a/9 = 84
28a = 756
a = 27
That means total 27 coins in a bag.
number of $5 coins = 4a/(4+3+2) = 4a/9
=4x27/9 = 12
There are 12 $5 coins in a bag.
2008-03-21 9:53 pm
1.(2a+b)/(3a+4b)=4/11
22a+11b=12a+16b
10a=5b
(10a/10b)=5b/10b
a/b=1/2
a : b=1:2
2.20x+6x+2x=84
x=84/28=3
3x4=12
22a+11b=12a+16b
10a=5b
(10a/10b)=5b/10b
a/b=1/2
a : b=1:2
2.20x+6x+2x=84
x=84/28=3
3x4=12
收錄日期: 2021-04-13 15:19:06
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080321000051KK01206