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by shikh » Sat Dec 03, 2011 2:01 am
S is an infinite sequence, in which the value of a particular member of the sequence is equal to the difference between the two preceding members of the sequence. What is the value of the 43rd member of the sequence?

(1) The 1st term is 1.
(2) The 3rd term is 3.

OA after discussion
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by sam2304 » Sat Dec 03, 2011 3:58 am
is the answer A ?

Initially i solved the question using both the statements but it seems we can solve it with A alone. The sequence repeats after 6 nos.

1.With 1st term as 1 the sequence repeats with every 6 nos. so 43rd term is equal to 1st term hence SUFF.

2nd term as 2 : 1 2 1 -1 -2 -1 1 2 1 -1 -2 -1 1
2nd term as 5 : 1 5 4 -1 -5 -4 1 5 4 -1 -5 -4 1

2.With the 3rd term as 3

2 5 3 -2 -5 -3 2
6 9 3 -6 -9 -3 6

Even in this sequence it follows a pattern based on the first digit. So with 3rd digit given we cannot find the answer and with 1st digit we can find it.

IMO A.
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by kanwar86 » Sat Dec 03, 2011 4:13 am
shikh wrote:S is an infinite sequence, in which the value of a particular member of the sequence is equal to the difference between the two preceding members of the sequence. What is the value of the 43rd member of the sequence?

(1) The 1st term is 1.
(2) The 3rd term is 3.

OA after discussion
IMO, C is the correct answer.
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by shikh » Sat Dec 03, 2011 4:44 am
OA is A
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by kanwar86 » Sat Dec 03, 2011 5:41 am
kanwar86 wrote:
shikh wrote:S is an infinite sequence, in which the value of a particular member of the sequence is equal to the difference between the two preceding members of the sequence. What is the value of the 43rd member of the sequence?

(1) The 1st term is 1.
(2) The 3rd term is 3.

OA after discussion
IMO, C is the correct answer.
Agree...silly mistake...answer is A)
Regards

Kanwar

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