Answered: SmithTelecome is a supplier to many…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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Question

SmithTelecome is a supplier to many brand-name makers of mobile phones. SmithTelecome manufactures the external shells that enclose mobile phones. The strength of a shell is measured by applying increasing pressure to the shell and recording the pressure at which the shell breaks. Shell strengths are approximately normally distributed. A random sample of 50 shells made by SmithTelecome showed an average strength of 30.0 pounds and a (sample) standard deviation of 5.0 pounds. a. By hand calculations (use only Excel, do not use StatTools), construct a 90% confidence interval for the mean shell strength. To determine the appropriate value of Z multiple, use either Excel function or the following Z values: z0.9 = 1.282, z0.95 = 1.645, z0.975 = 1.960, z0.99 = 2.326, z0.995 = 2.576 Present the confidence interval in the form point estimate ± margin of error. Show your work to receive full credit. b. Interpret the confidence interval within the context of the problem. c. What sample size is needed to have 90% confidence of estimating the population mean shell strength to within ± 0.5

Features Features Normal distribution is characterized by two parameters, mean (µ) and standard deviation (σ). When graphed, the mean represents the center of the bell curve and the graph is perfectly symmetric about the center. The mean, median, and mode are all equal for a normal distribution. The standard deviation measures the data's spread from the center. The higher the standard deviation, the more the data is spread out and the flatter the bell curve looks. Variance is another commonly used measure of the spread of the distribution and is equal to the square of the standard deviation.

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