Unformatted text preview: Student: Grady Simonton
Instructor: Shawn Parvini Date: 2/18/10 Course: Math119: Elementary Statistics  Spring 2.010  CRN: 492.39
 16 weeks Book: Triola: Elementary Statistics, 11e Time: 11:06 AMI The table below shows the frequency distribution of the
rainfall on 52 consecutive weekends in a certain city. Use
the frequency distribution to construct a histogram. Do the
data appear to have a distribution that is approximately
normal? class
0 — 0.19 2 0.20  0.39 5 0.40  0.59 12 0.60 — 0.79 15 0.80  0.99 1.00  1.19 1.20  1.39 The first task is to use the frequency distribution to create a
histogram. A histogram is a bar graph in which the horizontal scale
represents classes of data values and the vertical scale
represents frequencies. The heights of the bars correspond
to the frequency values, and the bars are drawn adjacent to
each other (without gaps). This histogram represents the data. 20— 10— 0 0.10.3 0.5 0.? 0.91.1 1.3 The next task is to decide whether the data appear to have a
distribution that is approximately normal. Key characteristics of the normal or "bell shape" are (1) the
rise in frequencies that reach a maximum, then decrease,
and (2) the symmetry with the left half of the graph that is
roughly a mirror image of the right half. If the graph does not appear to be normal, look at it to see
if the values are evenly distributed or skewed in a certain
direction. In this case, the frequencies match the description of the
normal curve since the data seems to be centered around
the values with maximum frequencies. Page 1 ...
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 Spring '10
 PARVINI

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