Question

- In a public examination, the standard score of Wilson is -3. The scores in the examination are normally distributed and there are 20 000 candidates in the examination. Find the percentage of candidates with scores higher than Wilson. ​

Answer 1

First of all, 50% of the scores are below the mean (80) and 50% are above (roughly). Approximately 68% of the data are within one standard deviation from the mean - 34% above and 34% below. A score of 87 is one standard deviation above the mean, correct? To answer "What percent scored less than 87?" We already know that 50% scored less than 80. We also know that 34% scored between 80 and 87. So 50% plus 34% is 84%. Let me make a video for this. A visual representation will make this WAY easier to understand.