During an epidemic, the R number refers to the number of cases of a disease that are directly caused by contact with one infected individual. During an epidemic, an individual becomes infected when the R number is 2. This means that during the first level of transmission, two further people will be infected who will each infect two more people during the second level of transmission. Predict the total number of people infected after four levels of transmission.

Scottish Highers Human Biology Problem Solving: During an epidemic, the R number

During an epidemic, the R number refers to the number of cases of a disease that are directly caused by contact with one infected individual - Scottish Highers Human Biology - Question 23 - 2023

Question 23

During-an-epidemic,-the-R-number-refers-to-the-number-of-cases-of-a-disease-that-are-directly-caused-by-contact-with-one-infected-individual-Scottish Highers Human Biology-Question 23-2023.png

During an epidemic, the R number refers to the number of cases of a disease that are directly caused by contact with one infected individual. During an epidemic, an... show full transcript

Worked Solution & Example Answer:During an epidemic, the R number refers to the number of cases of a disease that are directly caused by contact with one infected individual - Scottish Highers Human Biology - Question 23 - 2023

Step 1

First Level of Transmission

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Answer

At the start, we have 1 infected individual. After the first level of transmission, this individual infects 2 more people.

Step 2

Second Level of Transmission

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Each of the 2 newly infected individuals will infect 2 more people, resulting in: $2 imes 2 = 4$ additional infections.

Step 3

Third Level of Transmission

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The 4 new infections will again each infect 2 people, leading to: $4 imes 2 = 8$ additional infections.

Step 4

Fourth Level of Transmission

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Finally, these 8 new individuals will infect 2 people each, resulting in: $8 imes 2 = 16$ additional infections.

Step 5

Total After Four Levels

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Now, we sum up the total infected individuals: 1 (initial) + 2 (first level) + 4 (second level) + 8 (third level) + 16 (fourth level) = 31 individuals infected total.

During an epidemic, the R number refers to the number of cases of a disease that are directly caused by contact with one infected individual - Scottish Highers Human Biology - Question 23 - 2023

Worked Solution & Example Answer:During an epidemic, the R number refers to the number of cases of a disease that are directly caused by contact with one infected individual - Scottish Highers Human Biology - Question 23 - 2023

First Level of Transmission

Second Level of Transmission

Third Level of Transmission

Fourth Level of Transmission

Total After Four Levels

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