jlgdr wrote:
Eco Wildlife Preserve contains 5x zebras and 2x lions, where x is a positive integer. If the lions succeed in killing z of the zebras, is the new ratio of zebras to lions less than 2 to 1 ?
(1 ) z > x
(2 ) z = 4
Given: Eco Wildlife Preserve contains 5x zebras and 2x lions, where x is a positive integer. The lions kill z of the zebras Target question: Is the new ratio of zebras to lions less than 2 to 1 ?This is the perfect candidate for
rephrasing the target question.
ASIDE: If we take the time to rephrase the question in a simpler form, then we can save a ton of time evaluating the statements.
The NEW population of zebras is 5x - z
So, we can ask "
Is (5x - z)/2x < 2/1?"
Not bad, but
we can go much further than this!.
Since 2x is POSITIVE, we can safely take
(5x - z)/2x < 2/1 and multiply both sides by 2x.
When we do this, we get:
5x - z < 4xSubtract 4x from both sides:
x - z < 0Add z to both sides:
x < zSo, we can write....
REPHRASED target question: Is x < z?Now onto the statements....
Statement 1: z > x Perfect!!
The answer to the
REPHRASED target question is YES, x < z!Since we can answer the
REPHRASED target question with certainty, statement 1 is SUFFICIENT
Statement 2: z = 4Given this information, there is no way to conclude whether
x < zSince we cannot answer the
REPHRASED target question with certainty, statement 2 is NOT SUFFICIENT
Answer: A
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