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 240 bacteria.
Start Fraction n over 2 End Fraction 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.
2n=120; at 8:00 a.m., there were 240 bacteria.
n = number of bacteria at 9:00 a.m.
Since the culture doubles every hour, at 10:00 a.m. there will be 2n bacteria.
By working backwards, at 8:00 a.m. there will be n/2 bacteria.
Therefore, the equation that represents the number of bacteria, n, at 8:00 a.m. is:
n/2 = 120
To find the number of bacteria at 8:00 a.m., solve for n:
n = 2 * 120 = 240
So, at 8:00 a.m. there were 240 bacteria.
The correct answer is:
Start Fraction n over 2 End Fraction equals 120 ; at 8:00 a.m., there were 240 bacteria.