Rockwell hardness of pins of a certain type is known tohave a mean value of 50 and a standard deviation of 1.2.a. If the distribution is normal, what is the probabilitythat the sample mean hardness for a random sampleof 9 pins is at least 51?b. Without assuming population normality, what is the(approximate) probability that the sample meanhardness for a random sample of 40 pins is at least51?

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Estimation

A new framework of data analysis where the new statistical methods are used for interpreting the results and analyzing the data is known as estimation in statistics.