Answer:
Thursday's attendance was 9,315 visitors.
Explanation:
Given that the number of visitors triple each day.
Given that attendance on Monday = 345 visitors.
Tuesday's attendance = 3 x Monday's attendance = 3 x 345.
Wednesday's attendance = 3 x Tuesday's attendance = 3 x 3 x 345.
Thursday's attendance = 3 x Wednesday's attendance = 3 x 3 x 3 x 345 = 27 x 345 = 9,315 visitors.
Hence, Thursday's attendance was 9,315 visitors.