The time between release from prison and the commission of another crime is uniformly distributed between 0 and 5 years for a high-risk group. Give the equation and graph the pdf for X, the time between release and the commission of another crime for this group. What percent of this group will commit another crime within two years of their release from prison?
Solution
Let $X$ denote the time between release from prison and the commission of another crime uniformly distributed between 0 and 5 years.
$X\sim U(0, 5)$.
The probability density curve is
$$ \begin{aligned} f(x)=\left\{ \begin{array}{ll} \frac{1}{5 - 0}=0.2 , & \hbox{$0 \leq x\leq 5$;} \\ 0, & \hbox{Otherwise.} \end{array} \right. \end{aligned} $$
The graph of the pdf $f(x)$ is
The probability that the group will commit another crime within two years of their release from prison is
$$ \begin{aligned} P(X\leq 2) &= \int_{0}^{2} f(x) \; dx\\ &= \frac{1}{5-0}\int_{0}^{2} \; dx\\ &= 0.2\big[x\big]_{0}^{2} \\ &= 0.2\big[ 2- 0]\\ &= 0.4 \end{aligned} $$
Thus $40$ percent of this group will commit another crime within two years of their release from prison.
Further Reading
- Statistics
- Descriptive Statistics
- Probability Theory
- Probability Distribution
- Hypothesis Testing
- Confidence interval
- Sample size determination
- Non-parametric Tests
- Correlation Regression
- Statistics Calculators
