Answer:
the probability is 0.125
Step-by-step explanation:
The number of ways in which the mouse can move in the 4 turns is calculated using the rule of multiplication as:
<u> 2 </u>* <u> 2 </u> * <u> 2 </u>* <u> 2 </u> = 16
1st turn 2nd turn 3rd turn 4th turn
Because the mouse can take two options at every turn, right or left.
Now, from the 16 possibilities of movements, a mouse will find an exit in just two options:
1. right-right-left-left
2. left-right-right-left
So, the probability that a mouse will find an exit is:

Because, there are 16 possibilities and a mouse will find an exit using 2 of them.
Subtract the volume of the water from the volume of the tank to get the total volume of the marbles.
26 liters - 20.9 liters = 5.1 liters
He has 20.9 liters of water.
He has 85 marbles that add up to 5.1 liters of volume.
To find the volume of one marble, we divide 5.1 liters by 85.
(5.1 liters)/85 = 0.06 liters
The volume of each marble is 0.06 liters.
If he uses 200 marbles, the the marbles will occupy 200 * 0.06 liters = 12 liters.
The volume of the tank is 26 liters. 12 liters of volume is occupied by the marbles. The rest of the volume is water.
26 liters - 12 liters = 14 liters
24 months is the correct answer