After the first time, both barrels are 1/2.
After that, barrel B poured into barrel A for the nth time 1/(n+ 1).
Then barrel A pours 1/(n+2) into barrel B.
The available oil quantity of armored barrel is [1/2+1/(n+1)] [1-1(n+2)] =/kloc-0.
That is, it is reversed twice at a time and returns to 1/2.
So the odd number of times is 1/2.
25400 meters
Let a speed be x and b speed be y.
1200- 10x= 10y
100 x- 1200 = 100y
X=66,y=54。
And the value of 100y is the expected value.