rakeshd347 wrote:If sequence S has 240 terms, what is the 239th term of S ?
(1) Each term of S after the first term is 4 less than the preceding term.
(2) The 239th term of S is 952 less than the first term.
We need the 239th element of the sequence. So if we know the relationship among the elements of the sequence AND a
single value we can answer the question sufficiently.
Given: No of elements n = 240
Q: What is the 239th element i.e the last but one term?
St1:
sequence becomes : a, (a - 4), (a - 8), ... [a - (n - 1)4]
1st Term = a
2nd Term = a - (2 - 1)4
...
239th Term = a - (238)4 =
[a - 952]
240th Term = a - (239)4
We require a single value or the value of
a to find the last but one element, so INSUFFICIENT
St2:
239th element is 952 less than the first -->
a, ...
[a - 952]
We require a single value or the value of
a to find the last but one element, so INSUFFICIENT
St1+St2:
Combining the two statements essentially yield the same sequence:
a, [a - (1)4], [a - (2)4], ... [a - 952]
Here the last but one (239th) element is again
[a - 952]
Even after combining we are left with the same equation and again we cannot find the last but one element.
INSUFFICIENT
[spoiler]Answer : E[/spoiler]
Regards,
Vivek
