To determine the number of bacteria at 8:00 a.m., we need to understand that the culture doubles every hour. Given that there were 120 bacteria at 9:00 a.m., we can find the number of bacteria at 8:00 a.m. by dividing the 9:00 a.m. count by 2:
\[ \text{Number of bacteria at 8:00 a.m.} = \frac{120}{2} = 60 \]
Now, let's represent that with an equation. If we let \( n \) be the number of bacteria at 8:00 a.m., then at 9:00 a.m. we would have:
\[ 2n = 120 \]
Solving this:
- Divide both sides by 2: \[ n = \frac{120}{2} = 60 \]
Thus, at 8:00 a.m., there were 60 bacteria.
The correct response is:
2n = 120; at 8:00 a.m., there were 60 bacteria.
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