p1. Bahri lives quite close to the clock gadang in the city of Bukit Tinggi West Sumatra. Bahri has an antique clock. On Monday $4$th March $2013$ at $10.00$ am, Bahri antique clock is two minutes late in comparison with Clock Tower. A day later, the antique clock was four minutes late compared to the Clock Tower. March $6$, $2013$ the clock is late six minutes compared to Jam Gadang. The following days Bahri observed that his antique clock exhibited the same pattern of delay. On what day and what date in $2014$ the antique Bahri clock (hand short and long hands) point to the same number as the Clock Tower? p2. In one season, the Indonesian Football League is participated by $20$ teams football. Each team competes with every other team twice. The result of each match is $3$ if you win, $ 1$ if you draw, and $0$ if you lose. Every week there are $10$ matches involving all teams. The winner of the competition is the team that gets the highest total score. At the end what week is the fastest possible, the winner of the competition on is the season certain? p3. Look at the following picture. The quadrilateral $ABCD$ is a cyclic. Given that $CF$ is perpendicular to $AF$, $CE$ is perpendicular to $BD$, and $CG$ is perpendicular to $AB$. Is the following statements true? Write down your reasons. $$\frac{BD}{CE}=\frac{AB}{CG}+ \frac{AD}{CF}$$ p4. Suppose $M=2014^{2014}$. If the sum of all the numbers (digits) that make up the number $M$ equals $A$ and the sum of all the digits that make up the number $A$ equals $B$, then find the sum of all the numbers that make up $B$. p5. Find all positive integers $n < 200$ so that $n^2 + (n + 1)^2$ is square of an integer.
Problem
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Tags: algebra, geometry, number theory, combinatorics, indonesia juniors
BackToSchool
05.11.2021 07:48
$$M = 2014^{2014} < 2048^{2014} = 2^{22154} =4 \cdot (2^{13})^{1704} < 4 \cdot 10^{6816}$$\begin{align*}
A & < 3 + 9 \times 6816 = 61347 \\
B & < 5 + 4 \times 9 = 41\\
C & < 3 + 9 = 12
\end{align*}Note that
$$M = 2014^{2014} \equiv (-2)^{2014} \equiv ((-2)^6)^{335}\cdot 16 \equiv 7 \pmod 9$$$$M \equiv A \equiv B \equiv C \equiv 7 \pmod 9$$Therefore, the sum of all the digits that make up $B$ is $\boxed {7}$.
BackToSchool
06.11.2021 15:10
First, we need to make the gap of the scores between the team in the first place and the team in the second place as large as possible.
Thus, the team in the first place should win all the games and all other teams should be draw in all the games among them before the champion is certain.
Each team shall play $(20-1) \times 2 = 38$ games. Let X be the number of games when the champion is certain, we have:
$$3X > (X-1) + 3 (38-X) \implies X > \frac {113}{5} \implies X=\boxed {23}$$
BackToSchool
06.11.2021 23:39
In summary, the antique clock shall be two minutes later every day or every 24 hours. And the last time that the antique Bahri clock (hand short and long hands) pointing to the same number as the Clock Tower was on Sunday $3$rd March 2013 at 8:00 am.
It takes the Clock Tower $1440$ minutes for its hour hand and minute hand to return to their original place.
It takes Bahri's antique clock $1442$ minutes for its hour hand and minute hand to return to their original place.
The least common multiple of $1440$ and $1442$ is $1,038,240$.
Thus, it takes $1,038,240$minutes or $721$ days for the Clock Tower and Bahri's antique clock pointing the same number.
So on $22$nd February 2015 at 8:00 am, the Clock Tower and Bahri's antique clock pointed the same number again.