Answer:
The secondary attack rate is 55%
Step-by-step explanation:
Total number of students = 83
Primary cases: cases A+B+C = 3 primary cases.
Secondary cases = 44
Total cases = 44 + 3 = 47
To find the secondary attack rate, we are to assume that the primary cases are now immune because they had the illness.
We have:
Secondary attack rate = [tex] \frac{total cases - primary cases}{number of susceptible - primary cases} * 100[/tex]
[tex] = \frac{47-3}{83-3} * 100 [/tex]
[tex] = \frac{44}{80} * 100 = 55 [/tex]
The secondary attack rate is 55%