Topic: There are 12 table tennis characteristics, only one weight exception, now require a balance of the weight without weight three times, and find the weight of the ball.
My answer, I don't know if:
12 balls are numbered: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12
Divided into three piles: A disk: 1, 2, 3, 4
B disk: 5, 6, 7, 8
C disk: 9, 10, 11, 12
First call:
A and B are placed on both sides of the balance
1. If A = B, the abnormal ball is described in the C drive.
The second is said: Take 9, 10 placed in the A disk and 1, 2 to the B disk
(11) If A> B is, it will illustrate one of the abnormal balls of 9, 10.
The third time, said:
(111) Taking the ball 9 and the ball 1, if 10 is an abnormal ball, it is not equal to an abnormal ball.
(12) If a 2. If A> B, the abnormal ball is described in the top 8 balls, but it is not sure is in A or B, nor is it a heavy ball or a light ball. The second is said: 1, 6, 7, 9 is placed in the A disk, 5, 2, 10, 11 is placed in the B disk, 3, 4, 8, 12 is placed in the C disk, take the A disk and the b Comparison. (21) If A = B, it means that the abnormal ball is at the C disk, and it has been said that 9, 10, 11, 12 is normal, and it can be judged that the abnormal ball is 3, 4, 8. The third time, said: (211) Take 3, 4, if 3 = 4, the abnormal ball is a ball 8; if 3 is not equal to 4, the abnormal ball is 3, 4 one. At this time, the second weighing is the normal ball (5, 6, 7, 8 is normal), and A> B. It is known that the abnormal ball is a heavy ball, so it is called 3, 4 balls, take out A heavy ball is a normal ball. (22) If A> B, the second time is ordered as the A disk as the first weigh, but still does not judge the abnormality ball is a heavy ball or light ball, but it can be known that the abnormal ball is in the first and second times. Nothing moves, no moving balls are: 1, 5. The third time, said: (221) Take 1,9 two ball weighing, if 1 = 9, the abnormal ball is 5, otherwise the abnormal ball is 1. (23) If a The third time, said: (231) Since 6,7 two goals are from the B disk during the second weigh, take 6, 7 two ball weigh, if 6 = 7, the abnormal ball is the ball 2; if 6 is not equal, this When the second weighing is measured in the B disk, the 5, 2, 10, 11 balls are normal balls, and still A 3. If a
