F.2 ratio 文字題，help~!!!!!
John shares 100 marbles with Jack in the ratio 1 : 3. Jack then gives 45 of his marbles to Joseph. Find the ratio of John's number of marbles to that of Jack to that of Joseph.
Mary has 28 $5-coins, some $2-coins and some $0.5-coins. If the ratio of the value of $5-coins to that of $2-coins to that of $0.5-coins is 35 : 24 : 11, find
(a) the number of $ 2-coins Mary has,
(b) the ratio of the number of $5-coins to $2-coins to $0.5-coins
4 個解答
- ↑神奇化妝師↓Lv 69 年前最愛解答
John shares 100 marbles with Jack in the ratio 1 : 3.
so, John has 25 and Jack has 75
Jack then gives 45 of his marbles to Joseph.
so, Jack has 30 and Joseph has 45
the ratio of John's number of marbles to that of Jack to that of Joseph.
= 25 : 30 : 45
= 5 : 6 : 9
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2012-01-05 20:06:08 補充：
well...since someone copied my answers before and finally got the "best answer", i don't know this happen again.
2012-01-06 18:26:21 補充：
(a) let Mary has k $2-coins
28*5 : k*2 = 35 : 24
140 : 2k = 35 : 24
70 / k = 70 / 48
k = 48
2012-01-06 18:29:54 補充：
(b) let Mary has n $0.5-coins
28*5 : 48*2 : n*0.5 = 35 : 24 : 11
140 : 96 : 0.5n = 140 : 96 : 44
0.5n = 44
n = 88
ratio of the number of $5-coins to $2-coins to $0.5-coins is
28 : 48 : 88
= 7 : 12 : 22
資料來源： I am HKCEE MATH A grade, I am HKCEE MATH A grade, I am HKCEE MATH A grade - williamLv 59 年前
Mary has 28 $5-coins, some $2-coins and some $0.5-coins. If the ratio of the value of $5-coins to that of $2-coins to that of $0.5-coins is 35 : 24 : 11, find
(a) the number of $ 2-coins Mary has,
let A be the number of $2-coins
2 x A / (5 x 28 + 2 x A) = 24 / (24 + 35)
2A x 59 = 24 x (140 + 2A)
118A = 3360 + 48A
70A = 3360
A = 48
(b) the ratio of the number of $5-coins to $2-coins to $0.5-coins
Let B be the number of $0.5-coins
0.5 x B / (5 x 28 + 0.5 x B) = 11 / (11 + 35)
0.5B x 46 = 11 x (140 + 0.5B)
23B = 1540 + 5.5B
17.5B = 1540
B = 88
the ratio of the number of $5-coins to $2-coins to $0.5-coins :
28 : 48 : 88
= 7 : 12 : 22