close
Blogtrottr
Yahoo!奇摩知識+ - 分類問答 - 科學常識 - 已解決
Yahoo!奇摩知識+ - 分類問答 - 科學常識 - 已解決 
Free Bestselling eBooks

It's easy: sign up in under 10 seconds, tell us what kind of eBooks you love & we'll email you a list of deals every day - FREE! Join now!
From our sponsors
F.2 Maths(Rate & Ratio)20點!急!
Sep 9th 2014, 11:04

24.
(b)
2a = b
a/b = 1/2
a : b = 1 : 2 ...... [1]

3b = 2c
b/c = 2/3
b : c = 2 : 3 ...... [2]

From [1] and [2] :
a : b : c = 1 : 2 : 3

(c)
2a = 5b
a/b = 5/2
a : b = 5 : 2
a : b = 10 : 4 ...... [1]

5b = 4c
b/c = 4/5
b : c = 4 : 5 ...... [2]

From [1] and [2] :
a : b : c = 10 : 4 : 5

(d)
1/a : 1/b : 1/c = 2 : 3 : 4
a : b : c = 1/2 : 1/3 : 1/4
a : b : c = (1/2)×12 : (1/3)×12 : (1/4)×12
a : b : c = 6 : 4 : 3

Alternative method :
1/a : 1/b = 2 : 3
2/b = 3/a
a/b = 3/2
a : b = 3 : 2
a : b = 6 : 4 ...... [1]

1/b : 1/c = 3 : 4
3/c = 4/b
b/c = 4/3
b : c = 4 : 3 ...... [2]

From [1] and [2] :
a : b : c = 6 : 4 : 3

====
32.
Some words have been missed in the question :
"...... If B obtains $YYY than A ......"

====
34.
(a)
Let t kg be the weight of the tortoise, c kg be that of the cat, and d kg bethat of the dog.

t = (1/2)c
t/c = 1 : 2 ...... [1]

c = (1/4)d
c/d = 1/4
c : d = 1 : 4
c : d = 2 : 8 ...... [2]

From [1] and [2] :
(Weight of the tortoise) : (Weight of the cat) : (Weight of the dog)
= t : c : d
= 1 : 2 : 8

(b)(i)
Let k kg, 2k kg and 8k kg be the weights of the tortoise, cat and dogrespectively.

8k = 20
k = 2.5

The weight of the tortoise = k kg = 2.5kg

(b)(ii)
The total weight of the three pets
= (k + 2k + 8k) kg
= 11k kg
= 11 × 2.5 kg
= 27.5 kg

====
35.
Let n be the number of books that Angie borrowed from Leslie.

(48 + n) : (72 - n) = 13 : 17
17 × (48 + n) = 13 × (72 - n)
816 + 17n = 936 - 13n
30n = 120
n = 4

The number of books that Angie borrowed from Leslie = 4

====
37.
(a)
Let a, b and c be the number of $5-coins, $2-coins and 50¢-coins respectively.

5a : 2b : 0.5c = 35 : 24 : 11
5a/5 : 2b/2 : 0.5c/0.5 = 35/5 : 24/2 : 11/0.5
a : b : c = 7 : 12 : 22

Let 7k, 12k and 22k be the number of $5-coins, $2-coins and 50¢-coinsrespectively.

7k = 28
k = 4

The number of $2-coins
= 12 × 4
= 48

(b)
From (a), the numbers of $5-coins to $2-coins to 50-coins
= 7 : 12 : 22

參考資料 土扁

This entry passed through the Full-Text RSS service - if this is your content and you're reading it on someone else's site, please read the FAQ at fivefilters.org/content-only/faq.php#publishers.

You are receiving this email because you subscribed to this feed at blogtrottr.com.

If you no longer wish to receive these emails, you can unsubscribe from this feed, or manage all your subscriptions
arrow
arrow
    全站熱搜
    創作者介紹
    創作者 iwuisj 的頭像
    iwuisj

    線上遊戲排行榜2013/2014,進擊的巨人線上看,candy crush saga外掛,正妹寫真三圍

    iwuisj 發表在 痞客邦 留言(0) 人氣()