#### • Class 11 Physics Demo

Explore Related Concepts

# 1 standard deviation percentile

From Wikipedia

Percentile - Wikipedia, the free encyclopedia

The 25th percentile is also known as the first quartile (Q1); the 50th .... The dark blue zone represents one standard deviation on either side of the mean, ...

Question:

Answers:For z = -1/2 the percentile is 31. For z = -1 the percentile is 16. For z = 1/2 the percentile is 69. For z = 1 the percentile is 84.

Question:using a distribution with a mean of 100 and a standard deviation of 15. 1.What is the percentile score of a score of 112? 2.What is the percentile score of a score of 82?

Answers:Assuming it's a normal distribution... 112 is 12/15 = 0.8 standard deviations above the mean. So look up 0.8 on a normal distribution table. It'll be about 0.75. Which would mean 0.75 x 100 = 75 i.e. the 75th percentile. 82 is 18/15 = 1.2 standard deviations below the mean. So look up 1.2 on a normal distribution table (it'll be about 0.85), and then subtract that number from 1. (Very important to do this subtraction, because you are finding a number BELOW the mean). That will give you about 0.15. Multiply by 100 to get 15th percentile. Remember to replace the numbers I've given, with the actual numbers from the normal distribution table.

Question: