2.2.21 Consider the investigation of the manufacturing
process that is producing hypodermic needles. Recall that the
most recent random sample of 35 needles have an average
diameter of 1.64 mm and a standard deviation of 0.07 mm.
a. Use the Theory-Based Inference applet to fi nd and report
a standardized statistic (t-statistic) and a p-value to investigate
whether the average diameter of needles produced
by this manufacturing process is different from 1.65 mm.
b. Based on your p-value, write out a conclusion, being sure
to include justification.
2.2.7 An instructor collected data on the number of states
students in her class have visited in the U.S. A dotplot for the
collected data is shown below.
a. Identify the observational units.
b. Identify the variable recorded and whether it is categorical
c. Describe what the graph tells us about distribution of the
variable recorded. Be sure to comment on shape, center,
d. Use the dotplot to find and report the median value for
the number of states visited by the students in this study.
e. Would the mean value for these data be smaller than,
larger than, or the same as the median, as reported in (d)?
Explain your reasoning.
f. Suppose that the observation recorded as 43 states is a
typo and was meant to be 34. If we corrected this entry in
the data set, how would the following numerical statistics
change, if at all?
Mean: Smaller Same Larger
Median: Smaller Same Larger
Standard deviation: Smaller Same Larger
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