Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

I keep on coming into these problems while my gre prepration

How many times vs how many times greater or

a is what % of b or a is what % greater than b

What is the right convention to solve these problems? Some websites treat both of these scenarios similar? However I believe that in case of larger you have to do

if how many times b greater than a
do b-a/a.

Let's say a=9, b=3;

So I get these answers. Are these answers correct?

1: a is 3 times b.
2: a is 2 times greater than b.
3: a is 300% times b.
4: a is 200% times greater than b.

My confusion is that in this question, author does the opposite of what he should do.

share|improve this question
    
I am with you, but this may be rather a linguistic question and interpretation 2 is probably not as widespread (and becomes weird when $a=2b$ and you say $a$ is once greater than $b$) –  Hagen von Eitzen Oct 7 '13 at 17:59

2 Answers 2

up vote 2 down vote accepted

The phrase "A is what % of B" should be written as $A=x\cdot B$. And now solve for x, and then multiply by 100.

Example 1a: If A is 100, and B is 50, then $100=x\cdot 50$, means that $x = 2$, and A is 200% of B.

The phrase "A is what % greater than B," should be written as $A=x\cdot B$, just as before. But now, when you solve for x, and multiply by 100, you want to take the additional step of subtracting 100. Notice that this will only work if A is actually greater than B.

Example 1b: In the above example, A would be 100% greater than B.

Example 2: if A is 150, and B is 100, then solving for x in $A=x\cdot B$, would give us $x = 1.5$, and so A is 150% of B. But A is 50% greater than B.

share|improve this answer
    
You have a "greater than" mismatch between saying "A is 200% greater than B" in your second sentence vs. "example: In the above example, A would be 100% greater than B." in your fourth sentence. –  abiessu Oct 7 '13 at 18:05

The question that you link to uses the phrase "...how many times larger was...".

You use the phrase greater than in your question, and this is what causes the problem. There is an ambiguity about whether it is the comparative sizes of their differences that you discuss.

The fact is that 2 is two times larger than 1. The fact is that 1.5 is three times larger than 0.5. The fact is that $b$ is $(b \div a)$ times larger than $a$. The page you link to is correct.

share|improve this answer
    
If I understand correctly, you are saying it is larger vs greater? For greater and larger, answers will be different. –  Dude Oct 7 '13 at 18:16

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.