想問以下題目怎樣列公式:
If A is smaller than B by 10%,and B is smaller than C by 10%,
a.) by what percentage is A smaller than C?
b.) If D is greater than A by 20%, by what percentage is D greater or smaller
than C?
S1.maths percentage
2012-12-03 12:37 am
回答 (2)
2012-12-03 1:13 am
✔ 最佳答案
a)Let n be the value of C.
The value of B
= n(1 - 10%)
= 0.9n
The value of A
= 0.9n(1 - 10%)
= 0.81n
Percentage that A is smaller than C
= [(n - 0.81n)/n] x 100%
= 19%
=====
b)
The value of D
= 0.81n(1 + 20%)
= 0.972n
Since 0.972n < n, then B is smaller than C.
Percentage that B is small than C
= [(n - 0.972n)/n] x 100%
= 2.8%
參考: micatkie
2012-12-03 1:18 am
A = B(1 - 10%) = 0.9B........(1)
B = C(1 - 10%) = 0.9C ...........(2)
Sub (2) into (1), A = 0.9(0.9C) = 0.81C
a) % that A is smaller than C = (0.81C - C)/C x 100%
= - 0.19C/C x 100% = - 19%, that is 19% smaller than C.
b)
D = A(1 + 20%) = 1.2A = (1.2)(0.81C) = 0.972C
so % of D to C = (0.972C - C)/C x 100% = - 0.028 x 100% = - 2.8%
so D is smaller than C by 2.8%.
B = C(1 - 10%) = 0.9C ...........(2)
Sub (2) into (1), A = 0.9(0.9C) = 0.81C
a) % that A is smaller than C = (0.81C - C)/C x 100%
= - 0.19C/C x 100% = - 19%, that is 19% smaller than C.
b)
D = A(1 + 20%) = 1.2A = (1.2)(0.81C) = 0.972C
so % of D to C = (0.972C - C)/C x 100% = - 0.028 x 100% = - 2.8%
so D is smaller than C by 2.8%.
收錄日期: 2021-04-13 19:08:55
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20121202000051KK00251