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Exercise

Working with a beta curve

Suppose Rebekah's belief about P, the proportion of college women who believe they are overweight, can be described by a beta curve with shape parameters a = 8.13 and b = 3.67.

You can check out the curve on the right!

Using the pbeta() function, Rebekah's probability that the proportion P is smaller than 0.7 is equal to:

> pbeta(0.7, 8.13, 3.67)
[1] 0.5001066

Using the qbeta() function, the 0.25 quantile (or 25th percentile) of Rebekah's beta curve is given by

> qbeta(0.25, 8.13, 3.67)
[1] 0.6037313

Now it's your turn to play around with Rebekah's beta curve to gain some insights.

Instructions

100 XP
  • Find the probability P is smaller than 0.85.
  • Find the probability P is greater than 0.85.
  • Find the 75th percentile, or 0.75 quantile, of P.