A variable is normally distributed with mean 100 and standard deviation 10. Approximately what percentage of values lie between 90 and 110?
Answer and explanation
Correct answer: A. 68%
- Step 1: The interval is within 1 standard deviation of the mean, which holds about 68% of the values (the 68-95-99.7 rule).
Answer
68%.
Why not the others: 95%: uses the wrong standard deviation band. 50%: gives half the distribution. 99.7%: uses three standard deviations.
Practise more Functions, calculus and probability.
Free questions with an explanation for every one, and full timed Victorian VCE mock tests.