Question

Bradley bought groceries, including raw chicken, on an unseasonably warm fall day. Upon returning home, he forgot to bring the chicken into the house, and it was left in his warm car for 2 hours. Assume that when he brought the chicken back in the house there were a total of 2.0x10⁸bacteria in and on the raw chicken.  If the generation time is 15 minutes, how many bacteria were on the chicken to begin with?

Answer 1

Final bacterial concentration = 2.0 x 10⁸ bacteria

Generation time = 15 mins

Bradley left the chicken for = 2 hrs ( 120 mins)

Initial bacterial count = ?

Caluclation: First we calculate the time 2 hrs into parts of 15 mins

Therefore 2 hour = 8 X 15 mins (2 hrs can also be expressed as 8 parts of 15 mins each)

Now, We divide 2.0 x 10⁸ into 8 parts (of 15 mins) to get initial count

Initial bacterial count = 2 X 10^8 / 8

Initial bacterial count = 25000000 = 2.5 X 10^6

Therefore, there were 2.5 X 10^6 bacteria were on the chicken to begin with.