EMPOWERgmat DS Series:
Block 1, Question 2

Did the population of Country P increase by more than 25% from 2000 to 2005?

1) From 2000 to 2002, the population of Country P increased by 10% and from 2002 to 2005, the population of Country P increased by 14%
2) The Population of Country P in 2000 was 350,000 people


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OFFICIAL EXPLANATION

Hi All,

We're asked if the population of Country P increased by MORE than 25% from 2000 to 2005? This is a YES/NO question and can be solved in a couple of different ways, including logically (without doing any math) or TESTing VALUES.

1) From 2000 to 2002, the population of Country P increased by 10% and from 2002 to 2005, the population of Country P increased by 14%.

The information in Fact 1 gives us the necessary percentages to calculate what the overall percentage increase was from 2000 to 2005, so we would end up with a 'fixed' answer. Whether that value was more than 25% or not, it would be a definitive answer, so we would have the answer to the question - and thus, a Sufficient answer.

You can calculate the exact percentage increase in a couple of ways though:

Algebraically, it would be (X)(1.1)(1.14) = (1.1X)(1.14) = 1.254 = a 25.4% increase

With TESTing VALUES, let's set the initial population as 1,000.
The initial 10% increase would be 1,000 + (.1)(1,000) = 1,000 + 100 = 1,100
The next 14% increase would be 1,100 + (.14)(1,100) = 1,100 + 154 = 1,254
Total Percentage Increase = 1254/1000 = 1.254 = a 25.4% increase

Fact 1 is SUFFICIENT

2) The Population of Country P in 2000 was 350,000 people

Fact 2 tells us the 'starting number' of people in the year 2000, but tells us nothing about whether the population increased or decreased.
Fact 2 is INSUFFICIENT

Final Answer: A

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