To solve this problem, we need to find the time it takes for the number of bacteria to decrease from 25,000 to 1,250.
Given information:
- The initial number of bacteria is 25,000.
- The number of bacteria decreases by 65% every 3 hours.
- We need to find the time it takes for the bacteria to decrease to 1,250.
Step 1: Calculate the number of bacteria after each 3-hour interval.
Initial number of bacteria: 25,000
After 3 hours: 25,000 × (1 - 0.65) = 8,750
After 6 hours: 8,750 × (1 - 0.65) = 3,062.5
After 9 hours: 3,062.5 × (1 - 0.65) = 1,071.875
Step 2: Determine the time it takes for the bacteria to decrease to 1,250.
Since the number of bacteria after 9 hours is 1,071.875, which is less than 1,250, we can conclude that it will take between 9 and 12 hours for the bacteria to decrease to 1,250.
Step 3: Round the answer to the nearest thousand.
The time it takes for the bacteria to decrease to 1,250 is between 9,000 and 12,000 hours.
Rounding to the nearest thousand, the answer is 11,000 hours.
Therefore, it will take approximately 11,000 hours for the bacteria to decrease to 1,250.
