An article gave the following summary information for fracture strengths (mpa) of n = 169 ceramic bars fired in a particular kiln: x = 34.30, s = 3.92. calculate a (two-sided) confidence interval for true average fracture strength using a confidence level of 95%. (round your answers to two decimal places.) ) mpa does it appear that true average fracture strength has been precisely estimated? yes, this is a very narrow interval. no, this is a very wide interval. (b) suppose the investigators had believed a priori that the population standard deviation was about 4 mpa. based on this supposition, how large a sample would have been required to estimate to within 0.5 mpa with 95% confidence? ceramic bars you may need to use the appropriate table in the appendix of tables to answer this question.

Nthe opening scene of the movie raiders of the lost ark, indiana jones replaces a golden statue with a bag of sand. the platform on which the statue is placed is designed to detect the mass of the statue. if the bag of sand has a different mass than the statue, then a mechanism triggers and destruction ensues. the density of gold is about 20\text{ g/cm}^320 g/cm 3 20, space, g, slash, c, m, start superscript, 3, end superscript. the density of sand can be estimated at 2.5\text{ g/cm}^32.5 g/cm 3 2, point, 5, space, g, slash, c, m, start superscript, 3, end superscript. the gold statue can be modeled as a cylinder with height 25\text{ cm}25 cm25, space, c, m and radius 8\text{ cm}8 cm8, space, c, m. in terms of \piπpi, what is the mass of sand indiana jones needs to avoid triggering the mechanism?