Answer:
40 points
Step-by-step explanation:
The score for the first four rounds of the game is 13, 17, 19, and 21 points.
Let [tex]S_5[/tex] and [tex]S_6[/tex] be the scores of the fifth and sixth games respectively in order to achieve an average score of 20 points per round for all six rounds.
[tex]\text{Average score} = \frac{\text{Sum of the scores of all the rounds}}{\text{Total number of the rounds}}[/tex]
[tex]\Rightarrow 20=\frac{13+17+19+21+S_5+S_6}{6}[/tex]
[tex]\Rightarrow 20\times6=80+S_5+S_6[/tex]
[tex]\Rightarrow S_5+S_6=120-80=40.[/tex]
Hence, the combined score of the fifth and sixth rounds are 40 points.