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Statistics · Statistical distributions

Chapter 1 · 3

The idea

The continuous uniform distribution

When every value in an interval is equally likely: the rectangular probability density function, probability as length over width, the cumulative distribution function and quantiles, the mean, the variance and the exact value of E(X²), finding a and b from given facts, intervals that run past an end, and random cuts that split a length into pieces.

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Statistics · Statistical distributions

The continuous uniform distribution

When every value in an interval is equally likely: the rectangular probability density function, probability as length over width, the cumulative distribution function and quantiles, the mean, the variance and the exact value of E(X²), finding a and b from given facts, intervals that run past an end, and random cuts that split a length into pieces.

Why it works

Where will the rope snap?

A testing rig grips a 1414 m rope in two clamps, 11 m and 1313 m from end AA, and pulls until the rope snaps. The rope is the same all along, so no point between the clamps is more likely to break than any other. Let XX m be the distance of the snap from AA.1 m12 m1 mABclampclampHow likely is a snap more than 1010 m from AA? The stretch from 1010 to 1313 is 33 of the 1212 m between the clamps, so intuition says 312=14\frac{3}{12} = \frac14. This lesson turns that intuition into a model you can calculate with: the continuous uniform distribution.

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