Calculate the P value for this sequence alignment

Question

[Faris.Alkalim]

Hi guys, this is my second week in the bioinformatics world, so please excuse my basic question. How can I calculate the P value for this sequence alignment :

A query DNA sequence ACGTACGTA and database DNA sequence ACGTAAGTA have an alignment

ACGTACGTA ACATAAGTA

with similarity score 7.

N.B insertions and deletions are not allowed in sequence global alignment, and that the scoring scheme of global alignment is: score(match) = 1 and score(mismatch) = 0. Let X be a letter in random DNA sequence, Prob(X='A') = 0.25, Prob(X='C') = 0.25, Prob(X='G') = 0.25, and Prob(X='T') = 0.25.

[Jean-Karim Heriche]

This looks like a homework assignment. We won't do it for you. However, let us know what you've tried and where you're stuck and someone will surely help you.