adkikani wrote:
In a sequence of numbers in which each term is two more than the preceding term, what is the fourth term?
(1) Last term is 90
(2) First term is 2
Target question: What is the value of term_4? Statement 1: The last term is 90. We have no idea how many terms there are in the sequence. So, the last term could be term_5 or term_9 or term_12 or . . .
Consider these two possible cases:
Case a: The last term is term_6. In this case, term_6 = 90, term_5 = 88, term_4 = 86, term_3 = 84....etc. So, the answer to the target question is
term_4 = 86Case b: The last term is term_5. In this case, term_5 = 90, term_4 = 88, term_3 = 86 ....etc. So, the answer to the target question is
term_4 = 88Since we cannot answer the
target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: The first term is 2.If term_1 = 2, then: term_2 = 4, term_3 = 6, term_4 = 8, . .. etc
The answer to the target question is
term_4 = 8Since we can answer the
target question with certainty, statement 2 is SUFFICIENT
Answer: B
Cheers,
Brent
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Brent Hanneson – Creator of gmatprepnow.com
I’ve spent the last 20 years helping students overcome their difficulties with GMAT math, and the biggest thing I’ve learned is…
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