A culture of a certain bacteria doubles every hour. At 9:00 a.m, there were already 120 bacteria. Which equation represents the number of bacteria, n

, at 8:00 a.m? How many bacteria were there?(1 point)
Responses

n2=120
; at 8:00 a.m., there were 60 bacteria.
Start Fraction n over 2 End Fraction equals 120 ; at 8:00 a.m., there were 60 bacteria.

2n=120
; at 8:00 a.m., there were 240 bacteria.
2 n equals 120 ; at 8:00 a.m., there were 240 bacteria.

2n=120
; at 8:00 a.m., there were 60 bacteria.
2 n equals 120 ; at 8:00 a.m., there were 60 bacteria.

n2=120
; at 8:00 a.m., there were 240 bacteria.
Start Fraction n over 2 End Fraction equals 120 ; at 8:00 a.m., there were 240 bacteria.

1 answer

To find the number of bacteria at 8:00 a.m., we need to consider that the bacteria doubles every hour.

If we denote the number of bacteria at 8:00 a.m. as \( n \), then by 9:00 a.m. (which is one hour later), the number of bacteria would be \( 2n \).

Given that there are 120 bacteria at 9:00 a.m., we can set up the following equation:

\[ 2n = 120 \]

To find \( n \), we solve for \( n \):

\[ n = \frac{120}{2} = 60 \]

Thus, the equation that represents the number of bacteria at 8:00 a.m. is \( 2n = 120 \), and at 8:00 a.m., there were 60 bacteria.

So the correct response is:

2n = 120; at 8:00 a.m., there were 60 bacteria.