Why does juror 3 assume it was juror 5 who changed his vote?

Juror 3 assumes it was Juror 5 who changed his vote because he perceives Juror 5's background and experiences as a potential influence on his perspective regarding the case. Juror 5 grew up in a similar neighborhood to the accused, making Juror 3 believe he would sympathize with the defendant. This assumption is fueled by Juror 3's own biases and his desire to maintain the majority opinion. Additionally, he is frustrated with the shift in votes and looks for someone to blame for the change.