How do I calculate percent change

Forum Index GMAT Math

New MBA Student Life Forum: Ask your questions to current MBA students from Harvard, Stanford, Wharton, Kellogg and Haas

Post new topic   Reply to topic

boyerml
Just gettin' started!



Joined: 03 Nov 2009
Posts: 2

Thanks given: 1
Thanked 0 times in 0 posts
Topic: How do I calculate percent change
PostTue Nov 03, 2009 8:02 am Reply with quote
In the phrase

"has increased from 12.1 percent to 20.4 percent"

I would like to state that "disease" has increased by a certain percent. The difference here is 8.3%. So I need to know how I word this AND calculate it.

If I divide 12.1% by 20.4% I have a change (increase) of 59.3%

If I divide 8.3% by 12.1% my change is 68.6%.

Which is the most correct way to present the increase?

Which is the best wording to express that change:
"disease" has increased by xx.x%
or
"disease" has increased xx.x%

Thanks
Back to top
View user's profile Send private message
regor60
Just gettin' started!



Joined: 15 Oct 2009
Posts: 11

Thanks given: 0
Thanked 2 times in 2 posts
PostThu Nov 05, 2009 9:46 am Reply with quote
12.1/20.4 is a meaningless comparison since the base is the new base and you lose the "from" anchor.

You could say "the infected population has increased by 68.6%, or by 8.3% as a percentage of the entire population"
Back to top
View user's profile Send private message
Thanked by: boyerml
mjsobo
GMAT Instructor



Joined: 20 Sep 2009
Posts: 15

Thanks given: 0
Thanked 0 times in 0 posts
PostThu Nov 05, 2009 1:08 pm Reply with quote
the proper way to calculate percentage change is (d2-d1)/d1, where d2 is your new number. in simple terms, it is the delta (the change) divided by the original number. so in this case it is 8.3/12.1

And i agree with the response below, would be good to say that "the infected population has increased by 68%".

good luck!
_________________
Martin
GMAT Instructor with Grockit
Back to top
View user's profile Send private message Visit poster's website
boyerml
Just gettin' started!



Joined: 03 Nov 2009
Posts: 2

Thanks given: 1
Thanked 0 times in 0 posts
PostThu Nov 05, 2009 4:03 pm Reply with quote
Thanks to both of you. That always seemed to make more sense to me, but I was never sure and didn't want to over state the increase and lose credibility for the article. Thanks again

Michele
Back to top
View user's profile Send private message
Display posts from previous:   

Post new topic   Reply to topic All times are GMT - 8 Hours
Page 1 of 1