In a given population of 1000, new cases of lung cancer is 50, old cases in the same population are 100. What is the prevalence
**Core Concept**
Prevalence is a measure of the total number of cases of a disease in a population at a specific point in time, including both new and existing cases. It is calculated by dividing the total number of existing cases by the total population size.
**Why the Correct Answer is Right**
To calculate the prevalence of lung cancer in this population, we need to add the number of new cases to the number of old cases, and then divide the total by the population size. This will give us the proportion of the population that has lung cancer. The formula for prevalence is: Prevalence = (Number of existing cases + Number of new cases) / Total population. In this case, the number of existing cases is 100, the number of new cases is 50, and the total population is 1000.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not take into account the number of new cases of lung cancer in the population.
**Option B:** This option is incorrect because it does not use the correct formula to calculate prevalence.
**Option C:** This option is incorrect because it does not add the number of new cases to the number of existing cases.
**Option D:** This option is incorrect because it does not divide the total number of cases by the total population size.
**Clinical Pearl / High-Yield Fact**
Prevalence is an important measure of the burden of disease in a population, and can be used to monitor trends in disease incidence and to evaluate the effectiveness of public health interventions.
**Correct Answer: D. (100 + 50) / 1000 = 0.15 or 15%**