Question

TestScore

53

53

56

56

56

58

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58

59

59

59

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60

62

63

63

63

64

65

65

66

67

67

67

67

68

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69

69

71

71

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73

74

75

75

75

76

76

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76

77

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77

77

78

78

78

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79

79

79

80

80

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80

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81

81

81

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84

84

85

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90

90

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91

93

96

Take a random sample of 10 data values from "testscore" Using the sample that you selected, determine and state the sample mean. Compare the sample mean to the original confidence interval. Is the sample of 10 data values you selected a “good sample”? Explain why!

Answer #1

**Answer:**

Random Sample of size 10 taken is:

79 |

74 |

72 |

68 |

80 |

90 |

96 |

83 |

81 |

64 |

Sample mean using excel function AVERAGE(), x̅ = 78.7

Sample standard deviation using excel function STDEV.S(), s = 9.7188

Sample size, n = 10

95% Confidence interval :

At α = 0.05 and df = n-1 = 9, two tailed critical value, t-crit = T.INV.2T(0.05, 9) = 2.262

Lower Bound = x̅ - t-crit*s/√n = 78.7 - 2.262 * 9.7188/√10 = 71.75

Upper Bound = x̅ + t-crit*s/√n = 78.7 + 2.262 * 9.7188/√10 = 85.65

**71.75 < µ < 85.65**

The confidence interval of sample is wider than the population.

Mid Score
Final Score
80
78
87
85
72
81
69
54
86
70
83
73
78
89
75
84
74
86
75
79
84
75
73
63
74
72
73
69
80
86
75
78
72
75
77
68
76
77
66
78
74
77
71
73
85
79
74
74
76
79
76
73
84
72
77
81
78
86
86
76
81
83
78
83
85
86
73
71
83
83
83
79
72
68
83
90...

Below represent scores on an exam, each entry one score for one
student
40
99
59
98
63
63
64
65
67
35
67
67
68
70
71
71
71
46
72
72
60
73
74
74
74
75
97
75
62
76
76
76
76
76
77
57
77
98
77
63
78
78
78
79
79
80
80
80
80
80
81
81
92
81
93
82
82
83
83
83
83
83
83
83
84
84
84...

Use ? to approximate σ. Use a 5% level of significance.
Data:
69
62
75
66
68
57
61
84
61
77
62
71
68
69
79
76
87
78
73
89
81
73
64
65
73
69
57
79
78
80
79
81
73
74
84
83
82
85
86
77
72
79
59
64
65
82
64
70
83
89
69
73
84
76
79
81
80
74
77
66
68
77
79
78
77

Refer to the accompanying data set and construct a 95%
confidence interval estimate of the mean pulse rate of adult
females; then do the same for adult males. Compare the results.
Males Females
81
82
72
94
52
57
59
66
51
54
62
80
52
77
74
85
51
89
62
57
73
35
61
64
62
87
80
74
80
79
63
62
63
67
97
76
43
60
85
65
72
86
66
85
73
69
72 ...

Student Grades
Student
Test
Grade
1
76
62
2
84
90
3
79
68
4
88
84
5
76
58
6
66
79
7
75
73
8
94
93
9
66
65
10
92
86
11
80
53
12
87
83
13
86
49
14
63
72
15
92
87
16
75
89
17
69
81
18
92
94
19
79
78
20
60
71
21
68
84
22
71
74
23
61
74
24
68
54
25
76
97...

Question 1: Table 1 shows the number of customers visited by a
salesman over an 80-week period. Table 1: Customers Visited Over an
80-Week Period 68 64 75 82 68 60 62 88 76 93 73 79 88 73 60 93 71
59 85 75 61 65 75 87 74 62 95 78 63 72 66 78 82 75 94 77 69 74 68
60 96 78 89 61 75 95 60 79 83 71 79 62 67 97 78...

The following scores represent a sample of final examination
grades for a statistics course
23 60 98 32 57 74 52 70 82 69 74 63 80 62 80 77 81 95 41 65 92
85 85 61 36 79 55 76 52 10 64 75 78 25 80 48 83 64 88 82 81 67 41
71 67 54 34 72 74 43 60 78 84 89 76 84 17 90 15 79
a) Compute the 20th percentile of...

Using the accompanying Student Grades data, construct a scatter
chart for midterm versus final exam grades and add a linear
trendline. What is the model? If a student scores 7878 on the
midterm, what would you predict her grade on the final exam to
be?
Student
Midterm
Final Exam
1
75
64
2
85
91
3
80
68
4
88
83
5
76
60
6
67
80
7
78
74
8
95
94
9
67
61
10
93
87
11...

Test score of 40 students are listed below. Find the percentile for
the test score of 66.
30 35 43 44 47 48 54 55 56 57
59 62 63 65 66 68 69 69 71 72
72 73 74 76 77 77 78 79 80 81
81 82 83 85 89 92 93 94 97 98

Question 9-15 are based on the random
sample below which is obtained to test the following hypothesis
about the population mean. Test the hypothesis that the mean is
less than 80.
80
100
81
93
80
57
98
90
71
56
58
78
59
55
55
77
72
78
56
94
98
59
93
86
89
62
60
66
59
71
96
97
94
69
64
77
87
77
64
90
90
95
98
99
56
69
72
81
95...

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