Final answer:
The correct statements about histograms of binomial and geometric distributions are that a binomial distribution with p = 0.5 is always symmetric, and a geometric distribution's histogram is always decreasing.
Step-by-step explanation:
The student asks which statements are true regarding histograms of binomial distributions and geometric distributions. Regarding the binomial distribution:
- I. For p = 0.5, the binomial distribution is always symmetric, which is true because the probability of success and failure are the same.
- II. For p = 0.9, the binomial distribution is skewed to the right. This is false; with a high probability of success, the distribution is skewed to the left.
For the geometric distribution:
- III. The statement that the histogram of a geometric distribution is always decreasing is true. The probability of the first success decreases as the number of trials increases.
Based on the analysis, the correct answer is I and III.