
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
In a certain Samsung Cup Go final, the young player A defeated the reigning champion B with a score of 2:0, causing a sensation in the Go community of B's country! It is known that the Samsung Cup final adopts a best-of-three format, and the probability of player A defeating player B in a single match is $\frac{2}{5}$.  
(Ⅰ) Calculate the probability of player A defeating player B;  
(Ⅱ) If the format is changed to a best-of-seven, i.e., the number of matches player A needs to win against player B is denoted as X, calculate the expected value of X.

Present the answer in LaTex format: \boxed{Your answer}
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