A certain type of stainless steel powder is supposed to have a mean particle diameter of µ = 15 µm. A random sample of 87 particles had a mean diameter of 15.2 µm, with a standard deviation of 1.8 µm. A test is made of H0: µ = 15 versus H1: µ ≠ 15.

a. Find the P-value.

b. Do you believe it is plausible that the mean diameter is 15 µm?, or are you convinced that it differs from 15 µm? Explain your reasoning.

Section 3.1 STAT 250 David Holmes FEB 13 Numerical Summaries of Center and Variation Three characteristics of a numerical variable’s distribution: • Shape • Center (Typical Value) • Spread (Variability) Can a few numerical measures be used to describe a distribution’s entire shape NO Graphs provide the best overall picture of a distribution. Always plot your data. Measures of Center • Numeric values that represent the average or typical value of a numerical variable. • Arithmetic mean of a variable. (unimodal, symmetric) • Median of a variable. (unimodal, skewed and/or has outliers) • Mode of a variable. (categorical) • We can use the relationship among t