# Maths and English

• March 19th 2009, 10:16 AM
kenny1999
Maths and English
hello

first I am not speaking English as my first language, so this maybe due to language problem , I don't know.

What is the difference between "A is larger than B by 10%" and "B is smaller than A by 10%"
are they the same?

on the other hand.

A(1-10%)=B and
A=B(1+10%)

these two equations do not seem the same, so which one is to which English description?

hope someone explain
• March 19th 2009, 10:55 AM
HallsofIvy
Quote:

Originally Posted by kenny1999
hello

first I am not speaking English as my first language, so this maybe due to language problem , I don't know.

What is the difference between "A is larger than B by 10%" and "B is smaller than A by 10%"
are they the same?

on the other hand.

A(1-10%)=B and
A=B(1+10%)

these two equations do not seem the same, so which one is to which English description?

hope someone explain

First, don't write equations with percents- percents are not numbers and that is what is causing your confusion. Every percent requires knowing what base you are talking about. The first "A is larger than B by 10%" means that A is larger than B by 10% of B: A= B(1+ 0.10)= 1.1B. "B is smaller than A by 10%" means that B is less than A by 10% of A.
For example, if B= 100 and A= 110 then "A is 10% bigger than B": 10% of 100 is 10 and 100+ 10= 110. But 10% of A is 11 and 110- 11= 99, not 100. B is not "10% less than A".

By the way, your English is excellent. Far better than my ________ (put any language you like here!).
• March 20th 2009, 06:48 AM
Percentages
Hello kenny1999
Quote:

Originally Posted by kenny1999
..."A is larger than B by 10%" ...

$A = \frac{110}{100}B = \frac{11}{10}B$
Quote:

Originally Posted by kenny1999
..."B is smaller than A by 10%"

$B = \frac{90}{100}A=\frac{9}{10}A$
Quote:

Originally Posted by kenny1999
...are they the same?

No.