Two additives to Portland cement are being tested for their effect on the strength ofconcrete. 21 batches were made with Additive A, and their strengths showed standarddeviation s, = 41.3. 16 batches were made with the same percentage of Additive B,and their strengths showed standard deviation s, = 26.2. Assume that the strengths ofconcrete follow a normal distribution. Is there evidence at the 1% level of signifi-cance that the concrete made with Additive A is more variable than concrete madewith Additive B?

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Answered: Two additives to Portland cement are…

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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The blood platelet counts of a group of women have a bell-shaped distribution with a mean of 251.5 and a standard deviation of 69.1. (All units are 1000 cells/uL.) Using the empirical rule, find each approximate percentage below. a. What is the approximate percentage of women with platelet counts within 3 standard deviations of the mean, or between 44.2 and 458.8? b. What is the approximate percentage of women with platelet counts between 113.3 and 389.7? a. Approximately% of women in this group have platelet counts within 3 standard deviations of the mean, or between 44.2 and 458.8. (Type an integer or a decimal. Do not round.) b. Approximately % of women in this group have platelet counts between 113.3 and 389.7. (Type an integer or a decimal. Do not round.)
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