Once an individual has been infected with a certain disease, let X represent the time (days) that elapses before the individual becomes infectious. An article proposes a Weibull distribution with a = 2.6, ß = 1.7, and y=0.5. [Hint: The two-parameter Weibull distribution can be generalized by introducing a third parameter y, called a threshold or location parameter: replace x in the equation below, f(x; a, B)= Ba" E -²-1-(x/B) a 0 x 20 x < 0 by xy and x 20 by x ≥ y.] (a) Calculate P(1 < X < 2). (Round your answer to four decimal places.) x standard deviation (b) Calculate P(X> 1.5). (Round your answer to four decimal places.) X (c) What is the 90th percentile of the distribution? (Round your answer to three decimal places.) X days (d) What are the mean and standard deviation of X? (Round your answers to three decimal places.) mean X days X days

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Once an individual has been infected with a certain disease, let \( X \) represent the time (days) that elapses before the individual becomes infectious. An article proposes a Weibull distribution with \( \alpha = 2.6 \), \( \beta = 1.7 \), and \( \gamma = 0.5 \).

**Hint:** The two-parameter Weibull distribution can be generalized by introducing a third parameter \( \gamma \), called a threshold or location parameter: replace \( x \) in the equation below,

\[
f(x; \alpha, \beta) =
\begin{cases} 
\frac{\alpha}{\beta^\alpha} (x^{-\gamma})^{\alpha-1} e^{-(x^\gamma/\beta)^\alpha} & x \geq 0 \\
0 & x < 0 
\end{cases}
\]

by \( x - \gamma \) and \( x \ge \gamma \) by \( x \ge \gamma \).

---

**(a)** Calculate \( P(1 < X < 2) \). (Round your answer to four decimal places.)

\[ \text{[ ]} \hspace{1em} \times \]

---

**(b)** Calculate \( P(X > 1.5) \). (Round your answer to four decimal places.)

\[ \text{[ ]} \hspace{1em} \times \]

---

**(c)** What is the 90th percentile of the distribution? (Round your answer to three decimal places.)

\[ \text{[ ]} \text{ days} \]

---

**(d)** What are the mean and standard deviation of \( X \)? (Round your answers to three decimal places.)

\[
\begin{align*}
\text{mean} & \hspace{1em} \text{[ ]} \text{ days} \\
\text{standard deviation} & \hspace{1em} \text{[ ]} \text{ days}
\end{align*}
\]
Transcribed Image Text:Once an individual has been infected with a certain disease, let \( X \) represent the time (days) that elapses before the individual becomes infectious. An article proposes a Weibull distribution with \( \alpha = 2.6 \), \( \beta = 1.7 \), and \( \gamma = 0.5 \). **Hint:** The two-parameter Weibull distribution can be generalized by introducing a third parameter \( \gamma \), called a threshold or location parameter: replace \( x \) in the equation below, \[ f(x; \alpha, \beta) = \begin{cases} \frac{\alpha}{\beta^\alpha} (x^{-\gamma})^{\alpha-1} e^{-(x^\gamma/\beta)^\alpha} & x \geq 0 \\ 0 & x < 0 \end{cases} \] by \( x - \gamma \) and \( x \ge \gamma \) by \( x \ge \gamma \). --- **(a)** Calculate \( P(1 < X < 2) \). (Round your answer to four decimal places.) \[ \text{[ ]} \hspace{1em} \times \] --- **(b)** Calculate \( P(X > 1.5) \). (Round your answer to four decimal places.) \[ \text{[ ]} \hspace{1em} \times \] --- **(c)** What is the 90th percentile of the distribution? (Round your answer to three decimal places.) \[ \text{[ ]} \text{ days} \] --- **(d)** What are the mean and standard deviation of \( X \)? (Round your answers to three decimal places.) \[ \begin{align*} \text{mean} & \hspace{1em} \text{[ ]} \text{ days} \\ \text{standard deviation} & \hspace{1em} \text{[ ]} \text{ days} \end{align*} \]
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Can you please answer part D also?

Once an individual has been infected with a certain disease, let X represent the time (days) that elapses before the individual becomes infectious. An article proposes a Weibull distribution with a = 2.6, ß = 1.7, and
y = 0.5. [Hint: The two-parameter Weibull distribution can be generalized by introducing a third parameter y, called a threshold or location parameter: replace x in the equation below,
{2.
f(x; α, B) = Ba
-1e-(x/B) a
0
by x - y and x ≥ 0 by x ≥ y.]
(a) Calculate P(1 < X < 2). (Round your answer to four decimal places.)
0.4737
mean
x ≥ 0
x < 0
(b) Calculate P(X> 1.5). (Round your answer to four decimal places.)
0.7775
✓
(c) What is the 90th percentile of the distribution? (Round your answer to three decimal places.)
2.843
days
(d) What are the mean and standard deviation of X? (Round your answers to three decimal places.)
X days
X days
2.008
standard deviation 0.645
Transcribed Image Text:Once an individual has been infected with a certain disease, let X represent the time (days) that elapses before the individual becomes infectious. An article proposes a Weibull distribution with a = 2.6, ß = 1.7, and y = 0.5. [Hint: The two-parameter Weibull distribution can be generalized by introducing a third parameter y, called a threshold or location parameter: replace x in the equation below, {2. f(x; α, B) = Ba -1e-(x/B) a 0 by x - y and x ≥ 0 by x ≥ y.] (a) Calculate P(1 < X < 2). (Round your answer to four decimal places.) 0.4737 mean x ≥ 0 x < 0 (b) Calculate P(X> 1.5). (Round your answer to four decimal places.) 0.7775 ✓ (c) What is the 90th percentile of the distribution? (Round your answer to three decimal places.) 2.843 days (d) What are the mean and standard deviation of X? (Round your answers to three decimal places.) X days X days 2.008 standard deviation 0.645
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