Only one heavy ball is included in the balls whose form and size are same.
I think that I will find a heavy ball using an even balance by which heavier ball is found.
For example, when there is only one heavy ball in three balls, it is just once to find certainly a heavy ball by using even balance.
The number of times of using even balance should be lessened as much as possible.
Answer the following questions.
Noted that there is no limit of number of balls to be put on the even balance.
(1) In order to certainly find a heavy ball in 21 balls, find the minimum number of times using the even balance.
(2) Suppose that the even balance can be used only 4 times.
Find the most number of balls in which a heavy ball is certainly found.
I think that I will find a heavy ball using an even balance by which heavier ball is found.
For example, when there is only one heavy ball in three balls, it is just once to find certainly a heavy ball by using even balance.
The number of times of using even balance should be lessened as much as possible.
Answer the following questions.
Noted that there is no limit of number of balls to be put on the even balance.
(1) In order to certainly find a heavy ball in 21 balls, find the minimum number of times using the even balance.
(2) Suppose that the even balance can be used only 4 times.
Find the most number of balls in which a heavy ball is certainly found.
Answer
(1) 3 times
(2) 81 balls
(2) 81 balls
