| Date | November 2017 | Marks available | 1 | Reference code | 17N.1.SL.tz0.27 |
| Level | Standard Level | Paper | Paper 1 | Time zone | time zone 0 |
| Command term | What | Question number | 27 | Adapted from | N/A |
Question
What percentage of the normal distribution lies within ±1 standard deviation of the mean?
A. 98 %
B. 65 %
C. 95 %
D. 68 %
Markscheme
D
Examiners report
A challenging question in the mid-difficulty continuum with a good discrimination index. A, B, and C as distractors, which was surprising given the performance on the previous question.
Syllabus sections
Topic 6: Measurement and evaluation of human performance » 6.1. Statistical analysis » 6.1.3. State that the statistic standard deviation is used to summarize the spread of values around the mean, and that within a normal distribution approximately 68% and 95% of the values fall within plus or minus one or two standard deviations respectively.
