San Antonio Community College Statistics Worksheet

Learning Activity Modules 5 and 6Name_______________________
Date_______________________
Please show all work or no credit will be given. Make sure you are using Microsoft Word to
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1. According to the National Center for Health Statistics, 22.4% of adults are smokers. A random sample
of 300 adults is obtained.
a) Describe the sampling distribution of 𝑝̂ , the sample proportion of adults who smoke. (6 points)
b) In a random sample of 300 adults, what is the probability that at least 50 are smokers? (5 points)
c) Would it be unusual if a random sample of 300 adults results in 18% or less being smokers? Please
explain. (6 points)
2. Clayton Kershaw of the Los Angeles Dodgers is one of the premier pitchers in baseball. His most
popular pitch is a four-seam fastball. The data below represent the pitch speed (in miles per hour) for a
random sample of 18 of his four-seam fastball pitches.
Four
seam
fast
pitch
number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Speed
(miles per
hour)
93.63
93.83
94.18
94.71
95.52
95.07
95.12
94.75
95.35
94.70
94.15
95.28
94.62
95.49
96.08
95.77
93.86
93.34
a) Is “pitch speed” a quantitative or a qualitative variable? (1 point)
b) Draw a boxplot and check to see if the data set has any outliers. Does the data set has any outliers? (5
points)
c) Assuming the requirements for constructing a confidence interval for the mean are satisfied,
Construct and interpret a 95% confidence interval for the mean pitch speed of a Clayton Kershaw fourseam fastball. (6 points)