SAT Question of The Day 6th July 2013
, , ,, …
The first four terms of a sequence are shown above. Which of the following could be the formula that gives the th term of this sequence for all positive integers ?
One approach is plug in – n stands for the position of the term in the sequence.
If we plug in 1 to the formula instead of n we should obtain 3, when we plug in 2 we will get 6, 3 to give 11 and 4 to obtain 18.
Only n^2+2 delivers each time.
52% of 172,000 got it right.
P.S. in questions where plugging in seems to be the best option start from the last answer.