Answer:
1458
Step-by-step explanation:
If the bacteria started with just 2 at noon (12:00), in three hours the number of bacteria would have increased to 1458.
12:00- 2 bacteria
12:30- 2×3= 6 bacteria
13:00- 6×3= 18 bacteria
13:30- 18×3= 54 bacteria
14:00- 54×3= 162 bacteria
14:30- 162×3= 486 bacteria
15:00- 486×3= 1458 bacteria