Solution
Understanding the set :-
- There are 10 players – P1, P2, … , P10 - competed in an international javelin throw event, where 1,2,3... after "p" is his rank.
- Game was played in 2 phases -
a) First phase - rounds 1, 2, and 3 -
i) Players throw in increasing order of their rank
i.e., P1 throw first then P2...
ii) top six players at the end of the first phase qualify for the second phase.
b) Second phase - rounds 4, 5, 6 -
i) players throw in decreasing order of their latest rank
i.e., rank 6 throws first then rank 5...
- player's score at the end of a round is the maximum distance of all his throws up to that round.
This is a games and tournament set:
In this kind of set, the first paragraph is most crucial to understand as that will be the one, which will explain all the rules of the game, which is going to be the base point to solve the set.
ROUND -1
| Throw | Player |
|---|---|
| 1 | P1 |
| 2 | P2 |
| 3 | P3 |
| 4 | P4 |
| 5 | P5 |
| 6 | P6 |
| 7 | P7 |
| 8 | P8 |
| 9 | P9 |
| 10 | P10 |
We know, In first three rounds, players throw in increasing order of their rank.
ROUND - 2 :
| Player | Distance (in m) |
|---|---|
| P1 | 82.9 |
| P3 | 81.5 |
| P5 | 86.4 |
| P6 | 82.5 |
| P7 | 87.2 |
| P9 | 84.1 |
| Throw | Round 1 | Round 2 |
|---|---|---|
| 1 | P1 | P7 |
| 2 | P2 | P5 |
| 3 | P3 | P9 |
| 4 | P4 | P1 |
| 5 | P5 | P6 |
| 6 | P6 | P3 |
| 7 | P7 | P2 |
| 8 | P8 | P4 |
| 9 | P9 | P8 |
| 10 | P10 | P10 |
This is a table given in the set,
It shows Distances covered by all the valid throws in the first round.
=> in the first round P2, P4, P8 and P10, had invalid throw
therefore, "0" score.
Therefore, their rank will change in round 2 according to their round 1 scores.
| Throw | Round 1 | Round 2 |
|---|---|---|
| 1 | P1 | P7 (0) |
| 2 | P2 | P5 (0) |
| 3 | P3 | P9 (0) |
| 4 | P4 | P1 (0) |
| 5 | P5 | P6 (0) |
| 6 | P6 | P3 (0) |
| 7 | P7 | P2 (0) |
| 8 | P8 | P4 (0) |
| 9 | P9 | P8 |
| 10 | P10 | P10 |
Clue 1 says,
Among the throws in the second round, only the last two were valid.
=> In second round, except last two (P8 and P10 ) all had scored '0'.
=> Their rank will change in round 3 as,
P8 and P10 will move up in the table and occupy some higher places, whereas some of the others may move down consequently.
ROUND -3 :-
| Player | Distance (in m) |
|---|---|
| P1 | 88.6 |
| P3 | 79.0 |
| P9 | 81.4 |
| Throw | Round 1 | Round 2 | Winner |
|---|---|---|---|
| 1 | P1 | P7 | P1 |
| 2 | P2 | P5 | P7 |
| 3 | P3 | P9 | P5 |
| 4 | P4 | P1 | P9 |
| 5 | P5 | P6 | P8/P10 |
| 6 | P6 | P3 | P6 |
| 7 | P7 | P2 | P3 |
| 8 | P8 | P4 | P2 |
| 9 | P9 | P8 | P4 |
| 10 | P10 | P10 |
In Round 3, we can see that P1 improved his score from 82.9 to 88.6.
The other 2 participants did not improve their scores.
Also after Round 3, P8 and P10 qualify, where one of P8 or P10 is at the sixth position.
So at the end of Round 3, we can say that P6, P3, P2, and P4 are at the bottom 4 positions(ranks).
One of P8 or P10 is at the sixth position.
And, P1 > P7 > P5 > P9.
The other person between P8/P10 can go anywhere between Rank 1 and Rank 5.
Case -1 :
| Throw | Round 1 | Round 2 | Round 3 |
|---|---|---|---|
| 1 | P1 | P7 | P10 |
| 2 | P2 | P5 | P1 |
| 3 | P3 | P9 | P7 |
| 4 | P4 | P1 | P5 |
| 5 | P5 | P6 | P9 |
| 6 | P6 | P3 | P8 |
| 7 | P7 | P2 | P6 |
| 8 | P8 | P4 | P3 |
| 9 | P9 | P8 | P2 |
| 10 | P10 | P10 | P4 |
Case -2 :
| Throw | Round 1 | Round 2 | Round 3 |
|---|---|---|---|
| 1 | P1 | P7 | P1 |
| 2 | P2 | P5 | P10 |
| 3 | P3 | P9 | P7 |
| 4 | P4 | P1 | P5 |
| 5 | P5 | P6 | P9 |
| 6 | P6 | P3 | P8 |
| 7 | P7 | P2 | P6 |
| 8 | P8 | P4 | P3 |
| 9 | P9 | P8 | P2 |
| 10 | P10 | P10 | P4 |
Now let us consider the two players who got a double.
Doubles happen in the transition between rounds.
1 -> 2 - Not possible
2 -> 3 - Possible if P10 reaches Rank 1 after round 2.
3 -> 4 - P8/P10 who is the last among qualifying will be the first to throw. So, here it definitely happens.
4 - > 5
AND 5 - > 6 not possible.
So, after Round 2, definitely, P10 reaches the top of the ranking.
P8 is at the bottom.
Hence, after Round 3, P10 either retains rank 1 or P1 surpasses him and P10 becomes Rank 2.
| Throw | Round 1 | Round 2 | Round 3 |
|---|---|---|---|
| 1 | P1 | P7 | P1 |
| 2 | P2 | P5 | P10 |
| 3 | P3 | P9 | P7 |
| 4 | P4 | P1 | P5 |
| 5 | P5 | P6 | P9 |
| 6 | P6 | P3 | P8 |
| 7 | P7 | P2 | P6 |
| 8 | P8 | P4 | P3 |
| 9 | P9 | P8 | P2 |
| 10 | P10 | P10 | P4 |
Table before Round 4:
| Player | Distance (in m) |
|---|---|
| P1 | 88.6 |
| P7 | 87.2 |
| P5 | 86.4 |
| P9 | 84.1 |
Now, we know,
in each of the rounds in phase 2, only one player improves his score.
Also, P8 and P10 cannot win medals.
Hence, in case 1, three of P1, P7, P5 and P9 will improve their scores by x and reach the top 3 positions.
However, the top 3 positions' distances are in AP.
P1 - 88.6 + x
P7 - 87.2 + x
P5 - 86.4 + x
P9 - 84.1 + x
The differences do not satisfy the condition.
Hence, case 1 is invalidated.
| Throw | Round 1 | Round 2 | Round 3 |
|---|---|---|---|
| 1 | P1 | P7 | P1 |
| 2 | P2 | P5 | P10 |
| 3 | P3 | P9 | P7 |
| 4 | P4 | P1 | P5 |
| 5 | P5 | P6 | P9 |
| 6 | P6 | P3 | P8 |
| 7 | P7 | P2 | P6 |
| 8 | P8 | P4 | P3 |
| 9 | P9 | P8 | P2 |
| 10 | P10 | P10 | P4 |
| Player | Distance (in m) |
|---|---|
| P1 | 88.6 |
| P7 | 87.2 |
| P5 | 86.4 |
| P9 | 84.1 |
Here, P1 definitely wins a medal, and P10 does not.
So, two of P7, P5 and P9 jumps above P10.
Now, if we have three different people increasing their scores or distances in each of the three rounds, again we would not get a difference of 1 among the Gold, Silver and Bronze medalists.
Hence, one of them increases his score twice and the other increases his score twice and none of them is P1.
| Throw | Round 1 | Round 2 | Round 3 |
|---|---|---|---|
| 1 | P1 | P7 | P1 |
| 2 | P2 | P5 | P10 |
| 3 | P3 | P9 | P7 |
| 4 | P4 | P1 | P5 |
| 5 | P5 | P6 | P9 |
| 6 | P6 | P3 | P8 |
| 7 | P7 | P2 | P6 |
| 8 | P8 | P4 | P3 |
| 9 | P9 | P8 | P2 |
| 10 | P10 | P10 | P4 |
| Player | Distance (in m) |
|---|---|
| P1 | 88.6 |
| P7 | 87.2 |
| P5 | 86.4 |
| P9 | 84.1 |
Let us take the cases where P1 is individually the G, S and B medallists.
Case 1: P1 is a G medallist.
P1 - 88.6
The silver medalist is 87.6
and the bronze medalist is 86.6 metres.
However, P10 thrown for a distance that is greater than 87.2 metres. Hence, in this case, he would be the B medallist.
Hence, this is not the right case.
| Throw | Round 1 | Round 2 | Round 3 |
|---|---|---|---|
| 1 | P1 | P7 | P1 |
| 2 | P2 | P5 | P10 |
| 3 | P3 | P9 | P7 |
| 4 | P4 | P1 | P5 |
| 5 | P5 | P6 | P9 |
| 6 | P6 | P3 | P8 |
| 7 | P7 | P2 | P6 |
| 8 | P8 | P4 | P3 |
| 9 | P9 | P8 | P2 |
| 10 | P10 | P10 | P4 |
At the end of round 6 :-
| Player | Score |
|---|---|
| P7 | 89.6 |
| P1 | 88.6 |
| P5 | 87.6 |
| P10 | X |
| P9 | 84.1 |
| P8 | Y |
Case 2: P1 is the S medallist.
P1 - 88.6
G - 89.6
B - 87.6
Now, if we see the differences 89.6 - 87.2 = 2.4
87.6 - 86.4 = 1.2
This satisfies the condition that P7 has increased his score twice to become the gold winner and P5 has increased it once to become the bronze winner.
Hence, P1 - Silver
P7 - Gold
P5 - Bronze
| Throw | Round 1 | Round 2 | Round 3 |
|---|---|---|---|
| 1 | P1 | P7 | P1 |
| 2 | P2 | P5 | P10 |
| 3 | P3 | P9 | P7 |
| 4 | P4 | P1 | P5 |
| 5 | P5 | P6 | P9 |
| 6 | P6 | P3 | P8 |
| 7 | P7 | P2 | P6 |
| 8 | P8 | P4 | P3 |
| 9 | P9 | P8 | P2 |
| 10 | P10 | P10 | P4 |
At the end of round 6 :-
| Player | Score |
|---|---|
| P7 | 89.6 |
| P1 | 88.6 |
| P5 | 87.6 |
| P10 | X |
| P9 | 84.1 |
| P8 | Y |
From the table we can see that P1 got the silver medal
More from this set:
Question 1
Question 3