Consider a class with 100 enrolled students. None of the students were ill at the beginning of the school year. On September 30, a total of five students reported having gastroenteritis. All continued to be ill on October 1 but all five recovered in 3 days. On October 14, another three students developed gastroenteritis. All of these students continued to be ill on October 15, but all three recovered 5 days later. In this example, assume that a person cannot get gastroenteritis more than once. A. Calculate the pre-valence of gastroenteritis in the class on October 1.
B. Calculate the pre-valence of gastroenteritis in the class on October 30.
C. Calculate the cumulative incidence of gastroenteritis in the class during the month of October.

A. Calculate the prevalence of gastroenteritis in the class on October 1.

B. Calculate the prevalence of gastroenteritis in the class on October 30.

C. Calculate the cumulative incidence of gastroenteritis in the class during the month of October.

Step-by-step explanation:

Prevalence is calculated using the following formula:

(number of sick people / total number of people measured) x 100%

October 1 = (5 / 100) x 100% = 5%

October 30 = (0 / 100) x 100% = 0%

Cumulative = [3 / (100 - who got sick on September)] x 100% =  (3/95) x 100% = 3.16%

Since 5 students got sick during September, they cannot be included in the cumulative statistics for October. This means that the cumulative denominator will be 95, not 100.

step-by-step explanation:

you divide the denominator by the numerator on both sides and if the quotients are equal then the fractions are equivalent