pk6969 wrote:
Hi
IanStewart AndrewN If in the question, it would have been mentioned that its a series instead of sequence, then would that make D the correct option. Because there is always a relationship in a series. In a sequence its not always true. Am I right?
Hello,
pk6969. I did not think of any difference between
series and
sequence when I approached the question. If anything, the response that
IanStewart gave above should show that rigid thinking about words
when you are not absolutely sure of their meaning can get you into trouble. (To be fair to some prep companies and tutors, they may not know the mathematical definition of certain words and use them in a more general sense. But that does not mean that anybody, tutor, teacher, or prep company, should hide behind ignorance as an excuse not to improve on their understanding and teaching.)
Perhaps because I dabbled in intelligence testing in my teens and early twenties, statement (2) here looked rather familiar, like something on a "predict the next term" question. Trouble is, we are asked about the
thousandth term, and it is a long way to go from the first five terms to the one in question. I like the example
IanStewart gave in his post; my mind went straight to a different type of sequence:
Given: 1^2, 2^2, 3^2, 4^2, 5^2
Possible: 1^3, 2^3, 3^3, 4^3, 5^3
Without a way to pin down the behavior of the sequence
as a whole, I knew the proposition was dead in the water. (A) made sense; (B) (and, by extension, (D)) did not. I talk sometimes about the power of logic in my once-in-a-while Quant posts. These types of questions are my bread and butter, requiring little in the way of mathematical acumen to answer accurately and efficiently. (Again, I do not mean to excuse myself from improving my mathematical understanding. I am working on it all the time.)
- Andrew