Solve for z

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Which of the following are parts of a sphere

Aline has a slope of 1/4 and passes through point (0.4,-1/2). what is the value of the y-intercept?

The lengths of nails produced in a factory are normally distributed with a mean of 4.91 centimeters and a standard deviation of 0.05 centimeters. find the two lengths that separate the top 4% and the bottom 4%. these lengths could serve as limits used to identify which nails should be rejected. round your answer to the nearest hundredth, if necessary.