Chapter 4: Problem 26
Compute \(P\left(Y_{3}<\xi_{0.5}
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Chapter 4: Problem 26
Compute \(P\left(Y_{3}<\xi_{0.5}
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Let \(z^{*}\) be drawn at random from the discrete distribution which has mass \(n^{-1}\) at each point \(z_{i}=x_{i}-\bar{x}+\mu_{0}\), where \(\left(x_{1}, x_{2}, \ldots, x_{n}\right)\) is the realization of a random sample. Determine \(E\left(z^{*}\right)\) and \(V\left(z^{*}\right)\).
Twenty motors were put on test under a high-temperature setting. The lifetimes in hours of the motors under these conditions are given below. Suppose we assume that the lifetime of a motor under these conditions, \(X\), has a \(\Gamma(1, \theta)\) distribution. \(\begin{array}{cccccccccc}1 & 4 & 5 & 21 & 22 & 28 & 40 & 42 & 51 & 53 \\ 58 & 67 & 95 & 124 & 124 & 160 & 202 & 260 & 303 & 363\end{array}\) (a) Obtain a frequency distribution and a histogram or a stem-leaf plot of the data. Use the intervals \([0,50),[50,100), \ldots\) Based on this plot, do you think that the \(\Gamma(1, \theta)\) model is credible? (b) Obtain the maximum likelihood estimate of \(\theta\) and locate it on your plot. (c) Obtain the sample median of the data, which is an estimate of the median lifetime of a motor. What parameter is it estimating (i.e., determine the median of \(X\) )? (d) Based on the mle, what is another estimate of the median of \(X\) ?
In the baseball data set discussed in the last exercise, it was found that out of the 59 baseball players, 15 were left-handed. Is this odd, since the proportion of left-handed males in America is about \(11 \% ?\) Answer by using \((4.2 .7)\) to construct a \(95 \%\) approximate confidence interval for \(p\), the proportion of left-handed baseball players.
The data set on Scottish schoolchildren discussed in Example 4.1.5 included the eye colors of the children also. The frequencies of their eye colors are \(\begin{array}{lccl}\text { Blue } & \text { Light } & \text { Medium } & \text { Dark } \\ 2978 & 6697 & 7511 & 5175\end{array}\)
Assume that the weight of cereal in a "10-ounce box" is \(N\left(\mu, \sigma^{2}\right)\). To test \(H_{0}: \mu=10.1\) against \(H_{1}: \mu>10.1\), we take a random sample of size \(n=16\) and observe that \(\bar{x}=10.4\) and \(s=0.4\). (a) Do we accept or reject \(H_{0}\) at the \(5 \%\) significance level? (b) What is the approximate \(p\) -value of this test?
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