Difference between revisions of "2009 AMC 8 Problems/Problem 5"
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\textbf{(D)}\ 68 \qquad | \textbf{(D)}\ 68 \qquad | ||
\textbf{(E)}\ 99</math> | \textbf{(E)}\ 99</math> | ||
| + | |||
| + | ==Solution== | ||
| + | List them out, adding the three previous numbers to get the next number, | ||
| + | |||
| + | <cmath>1,2,3,6,11,20,37,\boxed{\textbf{(D)}\ 68}</cmath> | ||
==See Also== | ==See Also== | ||
{{AMC8 box|year=2009|num-b=4|num-a=6}} | {{AMC8 box|year=2009|num-b=4|num-a=6}} | ||
Revision as of 15:17, 25 December 2012
Problem
A sequence of numbers starts with 
, 
, and 
. The fourth number of the sequence is the sum of the previous three numbers in the sequence: $1\plus{}2\plus{}3\equal{}6$ (Error compiling LaTeX. Unknown error_msg). In the same way, every number after the fourth is the sum of the previous three numbers. What is the eighth number in the sequence?
Solution
List them out, adding the three previous numbers to get the next number,
![\[1,2,3,6,11,20,37,\boxed{\textbf{(D)}\ 68}\]](http://latex.artofproblemsolving.com/3/f/b/3fba5a20cd1e94a9ffbc9900192c13205d0fcc86.png)
See Also
| 2009 AMC 8 (Problems • Answer Key • Resources) | ||
| Preceded by Problem 4 |
Followed by Problem 6 | |
| 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 | ||
| All AJHSME/AMC 8 Problems and Solutions | ||
