Question

HW4 7-4. Suppose that samples of size n=25 are selected at ran- dom from a normal population with mean 100 and standard deviation 10. What is the probability that the sample mean falls in the interval from uly-1.70 touy +1.50 ? 7-5. A synthetic fiber used in manufacturing carpet has tensile strength that is normally distributed with mean 520 KN/m and standard deviation 25 KN/mp. Find the probability that a ran- dom sample of n= 6 fiber specimens will have sample mean tensile strength that exceeds 525 KN/m? 7-6. Consider the synthetic fiber in the previous exercise. How 7-14. A consumer electronics company is comparing the brightness of two different types of picture tubes for use in its television sets. Tube type A has mean brightness of 100 and standard deviation of 16, and tube type B has unknown mean brightness, but the standard deviation is assumed to be iden tical to that for type A. A random sample of n = 25 tubes of each type is selected, and X -X is computed. If ug equals or exceeds u A, the manufacturer would like to adopt type B for use. The observed difference is X - X = 3.5. What decision would you make, and why? 7-15. The elastic Flow Swirts. To remove the waterma n entipsions 7-29. Data on the oxide thickness of semiconductor wafers are as follows: 425. 431, 416, 420, 421, 436, 418, 410, 431, 433. 423, 426. 411, 435. 436, 428, 411.426. 407. 437. 422. 428, 413,416. (a) Calculate a point estimate of the mean oxide thickness for all wafers in the population. (b) Calculate a point estimate of the standard deviation of oxide thickness for all wafers in the population. (c) Calculate the standard error of the point estimate from part (a). (d) Calculate a point estimate of the median oxide thickness for all wafers in the population. (e) Calculate au point estimate of the proportion of wafers in P ore T30 options t e xtmate of the proportion or

Answer 1

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