5. The data below shows the heights in of sample of children in an MCH. 60cm,70cm,80cm,90cm ,100cm,110cm a. Calculate the standard deviation (6 marks) b. Interpret the results (2marks) 6. State four (4)types of host for disease causing microorganisms. (4 marks) 7. Explain any three (3) uses/applications of epĩdemiology. (6 marks) 8. Describe the pre -pathogenesis phase of natural History of disease. (3 marks)

5. a. To calculate the standard deviation, we first need to find the mean (average) of the data set. The mean is calculated by adding all the values together and dividing by the number of values.<br /><br />Mean = (60 + 70 + 80 + 90 + 100 + 110) / 6 = 85<br /><br />Next, we calculate the deviation of each value from the mean and square the result.<br /><br />(60 - 85)^2 = 625<br />(70 - 85)^2 = 225<br />(80 - 85)^2 = 25<br />(90 - 85)^2 = 25<br />(100 - 85)^2 = 225<br />(110 - 85)^2 = 625<br /><br />Now, we calculate the average of these squared deviations.<br /><br />Average = (625 + 225 + 25 + 25 + 225 + 625) / 6 = 325<br /><br />Finally, we take the square root of the average to get the standard deviation.<br /><br />Standard Deviation = √325 ≈ 18.03<br /><br />b. The standard deviation of 18.03 indicates the amount of variation or dispersion in the heights of the children in the sample. A lower standard deviation would mean that the heights are closely clustered around the mean, while a higher standard deviation would indicate a wider spread of heights.<br /><br />6. The four types of hosts for disease-causing microorganisms are:<br />1. Reservoir host: This is an organism or environment in which the disease-causing microorganism naturally resides and multiplies.<br />2. Intermediate host: This is an organism in which the microorganism undergoes development or multiplication before infecting the final host.<br />3. Definitive host: This is the organism in which the microorganism reaches its mature form and reproduces sexually.<br />4. Accidental host: This is an organism that is not normally infected by the microorganism but becomes infected due to accidental ingestion or transmission.<br /><br />7. Three uses/applications of epidemiology are:<br />1. Disease surveillance and monitoring: Epidemiology helps in tracking the occurrence and spread of diseases in a population, allowing for timely intervention and control measures.<br />2. Disease prevention and control: By studying the patterns and causes of diseases, epidemiologists can identify risk factors and implement strategies to prevent the occurrence of diseases.<br />3. Evaluation of public health interventions: Epidemiology is used to assess the effectiveness of public health interventions and policies, such as vaccination programs or health promotion campaigns.<br /><br />8. The pre-pathogenesis phase of the natural history of disease refers to the period before the onset of symptoms or disease manifestation. During this phase, the disease-causing microorganism may be present in the host without causing any noticeable symptoms. This phase is characterized by the microorganism's colonization and multiplication within the host, but the host remains asymptomatic. The duration of the pre-pathogenesis phase can vary depending on the specific disease and the individual host's immune response.