# Question: Population Increase

## Comment on Population Increase

### Hi Brent! In this question, I

Hi Brent! In this question, I think you have used the wrong value. It should be \$712.80 instead of 237..

https://greprepclub.com/forum/kathleen-s-weekly-salary-was-increased-by-8-percent-to-13649.html#p33761 ### Question link: https:/

The question (with \$237.60) is from the 2nd edition of the GRE Official Guide.
When the test-makers published the 3rd edition, they changed \$237.60 to \$712.80
I'm not sure why they did that.
The solution is the same, except we divide \$712.80 by 1.08 to get an answer of \$660

Cheers,
Brent

### Hi Brent, I did it

Hi Brent, I did it differently. I took the 2008 value and divided it by the 2007 value to get a 325% increase, then multiplied the 2008 value by 3.25. I got D. Is this an incorrect way to do the question? ### Your solution is perfectly

Your solution is perfectly valid. However, just to be clear about the terms, we can't say there was a 325% INCREASE, since it was actually a 225% increase.

However, we CAN say that the 2008 population was 3.25 TIMES the 2007 population.
Then, to find the 2009 population, we just MULTIPLY the 2008 population by 3.25

Cheers,
Brent

### Why did we add one in the new

Why did we add one in the new value and multiplyed it by 65000? ### Here are a few similar

Here are a few similar examples:

If x is increased by 10%, then the NEW value = x + (10% of x)
= x + 0.1x
= 1.1x

If x is increased by 50%, then the NEW value = x + (50% of x)
= x + 0.5x
= 1.5x

If x is increased by 90%, then the NEW value = x + (90% of x)
= x + 0.9x
= 1.9x

If x is increased by 100%, then the NEW value = x + (100% of x)
= x + x
= 2x

Likewise, if x is increased by 225%, then the NEW value = x + (225% of x)
= x + 2.25x
= 3.25x

Does that help?

Cheers,
Brent

### Hi Brent! I also completed

Hi Brent! I also completed this a little different as follows:
1. (65,008-19,984)/65,008 * 100 = about 69%
2. Then, I plugged in each answer choice to see which matches/is close to 69%
3. For ex: (210,000-65,008)/210,000 * 100 = 67%, so I went with choice D.

Is my technique applicable for these types of questions or was this a coincidence?
Thanks! ### You got a little lucky on

You got a little lucky on that question, because you calculated the percent increase incorrectly. However, you also tested the answer choices incorrectly, which allowed you to arrive at the correct answer :-)

In your solution, you are saying that percent increase = (100)(new - old)/NEW

The actual formula is as follows:
Percent increase = (100)(new - old)/OLD

So, as a percent increase = (65,008-19,984)/19,984 * 100
≈ 225%