1) A food truck company brings a sandwich to the MSU cafeteria at 12 noon. The
sandwich is supposed to be replaced (thrown away) by 2PM but instead it is sold to a
student at 5PM. The student dies at 6PM and officials find 9,600 colonies in her body at
6PM. If the culprit bacteria reproduce every hour, what was the initial amount of bacteria
in the sandwich
- Nt=9,600 (colonies found in the body at 6:00 PM)
Colonies found in the body at 6pm, 9,600
- No=? (initial colonies in the sandwich at 12:00 PM)
Bacteria doubles every hour, Nt= No x 2^n
9600= No x 2^6 → 9600=No⋅64 → No = 9600/64=150
- n=? (hours passed from 12:00 PM to 6:00 PM)
From 12 PM to 6pm is 6 hours, so n= 6
Final Answers: Nt=9,600
No= 150
n= 6
2) You are instructed to seed a sterile culture at noon with 300 bacteria and pick it up from
the incubator by 3PM. You are told the bacteria in the culture replicates every 1 hr. You
get entertained texting your friends and you forget about the culture and pick it up at 4PM
instead. What is the difference in the number of bacteria, From the time you were
supposed to pick it up to the time you actually picked it up?
- Nt= seeded the culture at 12:00 PM (noon) with No=300 bacteria.
Nt=No⋅2n, From 12:00 → 3:00 PM: n3=3 hours.
From 12:00 → 4:00 PM: n4=4 hours.
300×8=2400, 300×16=300×(10+6)=3000+1800=4800.
- No= given
300 seeded at noon
- n= supposed to pick it up at 3:00 PM but actually picked it up at 4:00 PM.
We need the difference in the number of bacteria between 3 PM and 4 PM.
3 hours to 3 PM, 4 hours to 4 PM (the difference in 𝑛 is 1 hour). Difference in bacteria between 3
PM and 4 PM: 2,400 additional bacteria.
Final Answers: Nt= 2,400 (3pm), 4,800 (4pm)
No= 300 seeded at noon
n= 2,400
This study source was downloaded by 100000898062787 from CourseHero.com on 09-30-2025 00:57:17 GMT -05:00
https://www.coursehero.com/file/251640673/In-class-assignment-1-MICROBIO-1pdf/
sandwich is supposed to be replaced (thrown away) by 2PM but instead it is sold to a
student at 5PM. The student dies at 6PM and officials find 9,600 colonies in her body at
6PM. If the culprit bacteria reproduce every hour, what was the initial amount of bacteria
in the sandwich
- Nt=9,600 (colonies found in the body at 6:00 PM)
Colonies found in the body at 6pm, 9,600
- No=? (initial colonies in the sandwich at 12:00 PM)
Bacteria doubles every hour, Nt= No x 2^n
9600= No x 2^6 → 9600=No⋅64 → No = 9600/64=150
- n=? (hours passed from 12:00 PM to 6:00 PM)
From 12 PM to 6pm is 6 hours, so n= 6
Final Answers: Nt=9,600
No= 150
n= 6
2) You are instructed to seed a sterile culture at noon with 300 bacteria and pick it up from
the incubator by 3PM. You are told the bacteria in the culture replicates every 1 hr. You
get entertained texting your friends and you forget about the culture and pick it up at 4PM
instead. What is the difference in the number of bacteria, From the time you were
supposed to pick it up to the time you actually picked it up?
- Nt= seeded the culture at 12:00 PM (noon) with No=300 bacteria.
Nt=No⋅2n, From 12:00 → 3:00 PM: n3=3 hours.
From 12:00 → 4:00 PM: n4=4 hours.
300×8=2400, 300×16=300×(10+6)=3000+1800=4800.
- No= given
300 seeded at noon
- n= supposed to pick it up at 3:00 PM but actually picked it up at 4:00 PM.
We need the difference in the number of bacteria between 3 PM and 4 PM.
3 hours to 3 PM, 4 hours to 4 PM (the difference in 𝑛 is 1 hour). Difference in bacteria between 3
PM and 4 PM: 2,400 additional bacteria.
Final Answers: Nt= 2,400 (3pm), 4,800 (4pm)
No= 300 seeded at noon
n= 2,400
This study source was downloaded by 100000898062787 from CourseHero.com on 09-30-2025 00:57:17 GMT -05:00
https://www.coursehero.com/file/251640673/In-class-assignment-1-MICROBIO-1pdf/
