Hi All,
This question can be solved with algebra or by TESTing THE ANSWERS. We're essentially asked to keep track of 4 years of data:
Last year
This year
Next year
2 yrs from now
We're told about the percentage increases in population over the last two years (10% each), but we're asked for the percentage increase from last year to this year (with the goal that the population has to DOUBLE over the course of all of these years).
Let's make last year's population = X
Now, let's TEST Answer B….40%
Last year = X
This year = 1.4X.... 10% of 1.4X = .14X, so....
Next year = 1.54X.... 10% of 1.54X = .154X, s....
2 years = 1.694X
This is an increase of 69.4%, which is TOO SMALL. We need a bigger percentage increase…
Let's TEST Answer D…65%
Last year = X
This year = 1.65X... 10% of 1.65X = .165X, so....
Next year = 1.815X... 10% of 1.815X = .1815X, so....
2 years = 1.9965X
This is an increase of 99.65%, which is just about DOUBLE. This is a MATCH for what we're looking for.
Final Answer:
GMAT assassins aren't born, they're made,
Rich
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