jimmyjamesdonkey wrote:
What was the percent increase in the population of City K from 1980 to 1990 ?
(1) In 1970 the population of City K was 160,000
(2) In 1980 the population of City K was 20 percent greater than it was in 1970, and in 1990 the population of City K was 30 percent greater than it was in 1970.
Target question: What was the percent increase in the population of City K from 1980 to 1990 ? Statement 1: In 1970 the population of City K was 160,000 Since we're given no information about the population in 1980 or 1990, it's impossible to answer the target question.
Statement 1 is NOT SUFFICIENT
Statement 2: In 1980 the population of City K was 20 percent greater than it was in 1970, and in 1990 the population of City K was 30 percent greater than it was in 1970.Let x = the population in 1970
So, 1.2x = the population in 1980
And 1.3x = the population in 1990
Percent increase = (100)(1990 population - 1980 population)/(1980 population)
= (100)(1.3x - 1.2x)/(1.2x)
= (100)(0.1x)/(1.2x)
= 10/1.2
So, the
percent increase = 10/1.2 percent (we need not actually evaluate the actual fraction)
Since we can answer the
target question with certainty, statement 2 is SUFFICIENT
Answer: B
Cheers,
Brent
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