An Introduction to Mathematical Statistics and Its Applications (6th Edition)

Published by Pearson
ISBN 10: 0-13411-421-3
ISBN 13: 978-0-13411-421-7

Chapter 4 Special Distributions - 4.3 The Normal Distribution - Questions - Page 242: 1

Answer

a) $\color{blue}{0.5782}$ b) $\color{blue}{0.8264}$ c) $\color{blue}{0.9306}$ d) $\color{blue}{0.0000}$

Work Step by Step

a) $\begin{align*} \int_{-0.44}^{1.33} \frac{1}{\sqrt{2\pi}}e^{-\frac{1}{2}z^2}\ dz &= P(Z\le 1.33) - P(Z\le -0.44),\quad Z\sim N(0,1) \\ &= F_Z(1.33) - F_Z(-0.44) \\ &= 0.9082 - 0.3300 \qquad \text{[ see Appendix Table A.1, pp. 675-6 ]} \\ \int_{-0.44}^{1.33} \frac{1}{\sqrt{2\pi}}e^{-\frac{1}{2}z^2}\ dz &= \color{blue}{0.5782} \end{align*}$ b) $\begin{align*} \int_{-\infty}^{0.94} \frac{1}{\sqrt{2\pi}}e^{-\frac{1}{2}z^2}\ dz &= P(Z\le 0.94) - P(Z\le -\infty),\quad Z\sim N(0,1) \\ &= F_Z(0.94) - F_Z(-\infty) \\ &= 0.8264 - 0 \qquad \text{[ see Appendix Table A.1, pp. 675-6 ]}\\ \int_{-\infty}^{0.94} \frac{1}{\sqrt{2\pi}}e^{-\frac{1}{2}z^2}\ dz &= \color{blue}{0.8264} \end{align*}$ c) $\begin{align*} \int_{-1.48}^{\infty} \frac{1}{\sqrt{2\pi}}e^{-\frac{1}{2}z^2}\ dz &= P(Z\le \infty) - P(Z\le -1.48),\quad Z\sim N(0,1) \\ &= F_Z(\infty) - F_Z(-1.48) \\ &= 1 - 0.0694 \qquad \text{[ see Appendix Table A.1, pp. 675-6 ]}\\ \int_{-1.48}^{\infty} \frac{1}{\sqrt{2\pi}}e^{-\frac{1}{2}z^2}\ dz &= \color{blue}{0.9306} \end{align*}$ d) $\begin{align*} \int_{-\infty}^{-4.32} \frac{1}{\sqrt{2\pi}}e^{-\frac{1}{2}z^2}\ dz &= P(Z\le -4.32) - P(Z\le -\infty),\quad Z\sim N(0,1) \\ &= F_Z(-4.32) - F_Z(-\infty) \\ &= 0.000 0- 0.0000 \qquad \text{[ see Appendix Table A.1, pp. 675-6 ]}\\ \int_{-\infty}^{-4.32} \frac{1}{\sqrt{2\pi}}e^{-\frac{1}{2}z^2}\ dz &= \color{blue}{0.0000} \end{align*}$
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