Answer:
4 amino acids.
Explanation:
To become translated into protein, a sequence is read in triplets called codons.
Each codon that codes for an amino acid is made up of 3 nucleotides.
Therefore, a sequence of 15 nucleotides would be translated into a polypeptide that is made up of 5 amino acids. (15 divided by 3 = 5)
However, we are told that there is a stop codon at the end of this sequence.
A stop codon is a specialised codon that does not code for an amino acid, but tells the protein machinery that the polypeptide is complete.
Therefore, the polypeptide would have 5-1 amino acids, which corresponds to 4 amino acids.