In the history of NBA, many champion teams have featured two star players. For example, 2000-2001 and 2001-2002 LA Lakers featured Shaquille O'Neal and Kobe Bryant, 2019-2020 LA Lakers featured LeBron James and Anthony Davis. Having one-two punches in a team can reduce the chance of inconsistent performance by compelementing each other. Suppose that two star players in the same team, A and B, have the following stats in a season: Player A's average points per game 25 with the standard deviation of 5. Player B's average points per game 20 with the standard deviation of 4. The correlation coefficient between their points per game is -0.125. Find the standard deviation of the sum of the two player's points per game