Topic: There are 12
The table tennis characteristics are the same, only one weight exception is required, and now you need to use a balance of the weight without weight three times, and find the weight of the ball. Here is the answer =========================== answer inspiration: Yesterday's misunderstanding when considering. Now explain:
It is entirely possible to find an abnormal ball in three balls.
Why is this? It is completely possible in three balls to find abnormal balls, but there is a premise: these three balls must be called the balance, know that it is heavy or light. (Figure 1)
Assuming that the three balls on the left red zone finally said that it is abnormal, the green area is normal. Then you can find an exception ball. (As shown)
2
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Take out one of the three red balls, then select one of the other two. Because just the red area is abnormal (as shown in Figure 1, this is very important. How to know how he is below the left.), So immediately got the answer.
Possibleity 1: balance balance. Then the ball taken is an abnormality.
Possibility 2: There is still no change in balance. Then the left ball is abnormal.
Possibility 3: Extreme low changes. So right-ball is abnormal.
Ok, three goals find a ball principle know. The following is decomposed, and three in twelve balls.
We divide twelve balls: average is divided into three copies. All four balls. (Figure 3) First, the red and green predominth. Two possibilities:
Possibleity 1: balance balance. Explain the abnormal ball in the black zone.
Possibility 2: Balance is unbalanced. Explain that the abnormal ball is in red or green zone.
First consider the possibility 1: balance balance. Then the abnormal ball in the black area.
Red and green for normal ball. At this time, we only need to divide the black ball average into two copies, each with two balls. One of them selected two balls in red or green balls. The last two balls can be obtained (one anomaly). At this time, the two balls can be divided into two copies. When the normal ball is called, it can draw an abnormal ball.
Possibility 2: Balance is unbalanced.
Explain that the abnormal ball is in red or green zone. The black area is normal. Then take out two red balls, four green balls take a salary out, get three balls (one green two red). The other five balls (two red three green) were then divided into two copies. A copy is a red and green, another red and green. Put these two copies in the balance. That is, three possibilities are obtained (Figure 4):
Possibleity 1: The height of the balance has not changed. Note Abnormal balls are only in the top two balls (red green).
Possibility 2: Extreme low changes. Explain that the abnormal ball is in two green and right red balls on the left.
Possible three: balance balance. Note There is an exception in the three balls taken out.
Solution one:
One of the two balls is normally referred to. The answer is now coming.
Solution 2:
Take one of two greens with another red, according to the first weighing balance, it can draw an abnormally ball out. The method of finding a ball with three goals has been explained.
Solution 3:
Take one of the two red and another green. According to the first weighing balance, it is called high. You can get an abnormal ball. (Solution is the same as the possibility). It is also a way to find a ball with three goals.
complete! ^ o ^
