Answer:
Day 10
Step-by-step explanation:
If the number of bacteria increases by a factor of two each day (i.e. it doubles), it will reach 5120 by day 10. At this rate, the colony likely started with 10 bacteria on day one and doubled each day to reach 320 by day 6.
Day 6- 320 bacteria
Day 7- 320×2= 640 bacteria
Day 8- 640×2= 1280 bacteria
Day 9- 1280×2= 2560 bacteria
Day 10- 2560×2= 5120 bacteria