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

Question

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

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

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

Answer 1

To determine the number of bacteria at 8:00 a.m., we need to work backwards from the known amount at 9:00 a.m., which is 120 bacteria. Since the bacteria double every hour, we can represent the number of bacteria at 8:00 a.m. using the following relationship:

At 9:00 a.m., there are 120 bacteria, which means that at 8:00 a.m., the number of bacteria was half of that:

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

Now, we want to write an equation that represents this relationship (the number of bacteria at 8:00 a.m. in relation to the 9:00 a.m. count):

If \( n \) is the number of bacteria at 8:00 a.m., then:

\[ 2n = 120 \]

This means that the equation 2n = 120 correctly models the relationship.

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