STAT 1124 Quiz 2 Model Answers

STAT 1124 Quiz 2 Model Answers - c) What is the sample...

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STAT 1124 Section 2 Name: Quiz 2 Student ID: February 2, 2009 You have 20 minutes to complete the following 1. Given the following table that summarizes a sample: x i x i - xbar (x i - xbar) 2 15.9 -1.45 2.10 16.0 -1.35 1.82 16.4 -0.95 0.90 16.7 -0.65 0.42 16.8 -0.55 0.30 16.9 -0.45 0.20 17.0 -0.35 0.12 17.0 -0.35 0.12 17.1 -0.25 0.06 17.2 -0.15 0.02 17.2 -0.15 0.02 17.3 -0.05 0.00 17.5 0.15 0.02 17.7 0.35 0.12 17.8 0.45 0.20 17.9 0.55 0.30 18.3 0.95 0.90 18.4 1.05 1.10 18.5 1.15 1.32 19.4 2.05 4.20 Count 20 20 20 Sum 347.000 0.000 14.290 a) Choose a graphical tool to represent the data (e.g., histogram, Boxplot, or a Stemplot) ( 3 ) It is not advisable to construct a histogram in this case; it is too time consuming. Boxplot: Min=15.9, Q1=16.85, Median = 17.2, Q3=17.85, Max=19.4
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The easiest is the Stemplot: Stemplot 15| 9 16| 04789 17| 0012235789 18| 345 19| 4 b) What is the sample mean? ( 1 ) Sample Mean = 347/20 = 17.35
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Unformatted text preview: c) What is the sample standard deviation? ( 1 ) Sample standard deviation = SQRT(14.290/19) = 0.867 d) How would you, in one sentence, describe the distribution of this sample (symmetric, or skewed, etc.) ( 1 ) The distribution is nearly symmetric. It is slightly skewed to the right . 16.85 17.2 17.85 19.4 15.9 2. Given the following Stemplot, 1 |1 2| 456789 3| 2234556789 4| 012 a) Find the Minimum? ( 1 ) Minimum = 11 b) Find Q1? ( 1 ) Q1 = (27+28)/2 = 27.5 c) Find the Median? ( 1 ) Median = (33+34)/2 = 33.5 d) Find Q3? ( 1 ) Q3 = (37+38)/2 = 37.5 e) Find the Maximum? ( 1 ) Maximum = 42 f) Construct a Box plot ( 2 ) g) Is there an outlier? Use the 1.5 times IQR rule to justify your answer. ( 2 ) IQR = 37.5 27.5 = 10 1.5 * IQR = 1.5 x 10 = 15.0 Q1 - 1.5 * IQR = 27.5-15.0 = 12.5 11 is an outlier since 11 < 12.5 42 is obvious not an outlier as 42-38 = 4 < IQR 27.5 33.5 37.5 42 11...
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This note was uploaded on 07/14/2010 for the course STATS 1124 taught by Professor Michael during the Summer '09 term at Langara.

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STAT 1124 Quiz 2 Model Answers - c) What is the sample...

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