Descriptive Statistics III - Measures of Dispersion MCQs

Sex ratio is number of females as per 1000 males in the population A sex ratio of more than 1000 indicates that for every 1000 males, there are > 1000 females. That means more than 50% are females. Therefore, if the total population is 10000, and the sex ratio is more than 1000, it means that the number of females are more than 5000 and males are less than 5000 Reference: Park's Preventive and social medicine, 27th EDITION Pg 558

The coefficient of variation (CV) is a measure of relative variability, expressed as a percentage. It is calculated as the ratio of the standard deviation (SD) to the mean, multiplied by 100. Given: Mean weight of 100 children = 12 kg Standard deviation (SD) = 3 kg The formula for the coefficient of variation (CV) is: CV = (SD/MEAN) × 100 CV = (3/12) × 100 = .025 * 100 = 25% So, the correct answer is a. 25% Therefore, the correct percent coefficient of variation for the given data is option A. 25%. Reference: Park's Preventive and social medicine, 27th EDITION Pg 980

If mean is 20, +- 1 SD = 20+5 to 20-5 = 25 to 15. This covers 68% of all data. Thus, we know 95% of data is covered in mean +/- 2SD, thus the range shall be 20 +/- 2*(SD) = 20+/- 2*(5) = 20 +/-10. Thus the final range comes out to be 10-30. Reference - Park's Preventive and social medicine, 27th EDITION Pg 976