MathDB

26

Part of 2001 National Olympiad First Round

Problems(1)

P26 [Combinatorics] - Turkish NMO 1st Round - 2001

Source:

4/23/2014
Berk tries to guess the two-digit number that Ayca picks. After each guess, Ayca gives a hint indicating the number of digits which match the number picked. If Berk can guarantee to guess Ayca's number in nn guesses, what is the smallest possible value of nn?
<spanclass=′latex−bold′>(A)</span> 9<spanclass=′latex−bold′>(B)</span> 10<spanclass=′latex−bold′>(C)</span> 11<spanclass=′latex−bold′>(D)</span> 15<spanclass=′latex−bold′>(E)</span> 20 <span class='latex-bold'>(A)</span>\ 9 \qquad<span class='latex-bold'>(B)</span>\ 10 \qquad<span class='latex-bold'>(C)</span>\ 11 \qquad<span class='latex-bold'>(D)</span>\ 15 \qquad<span class='latex-bold'>(E)</span>\ 20