Question

The average grade obtained on the test by its 25 students is an 83, with a standard deviation of 11 points.

a. Approximately how many people received a failing grade (less than 65)?

b. What percentage of people received a grade between a 70 and a 91?

c. What percentage of individuals received a score whose z-score was -.70 or less?

d. What grade is required in order to be in the top 15 percent? The top 10 percent?

e. What percentage of people received a grade between 85 and 95?

f. What percentage of people received a grade of 94 or less?

g. What grade is required to be in the bottom 20%?

h. What z-score is required to be in the top 40%?

i. What percentage of individuals have a z-score between -1 and 1.40?

j. What percentage of individuals have a z-score between 1.05 and 1.40?

Answer #1

QUESTION 22 The results from a statistics class' first exam are
as follows: The mean grade obtained by its 25 students is 83, with
a standard deviation of 11. The distribution of grades was unimodal
and symmetrical. What percentage of individuals have a z-score
between -1 and 1.40 QUESTION 23 Suppose you have a tree farm and
you have 1000 live oaks on this farm. You are wondering if this
would be a profitable time to harvest the tallest ones...

8. In a
statistics class, the average grade on the final examination was 75
with a standard deviation of 5.
a.
Use Chebyshev’s theorem to answer: At least what percentage of
the students received grades between 50 and 100?
b.
What is the z-score for a student who had an examination score
of 91?
c. Would the test score from part b., be
considered an outlier? Explain.
9. Assume we have a symmetric or bell shaped distribution. Using...

1a.) The following grades were obtained on the Research Methods
course of students of the Urban Studies Department at Stanford
University (70, 90, 85, 70, 85, 60, 95, 50, 65, 70). There were 95
students in the class. Variance of the data set is:
a.144
b.214
c.184
d.None of the above
1b.) The following grades were obtained on the Research Methods
course of students of the Urban Studies Department at Stanford
University (70, 90, 85, 70, 85, 60, 95, 50,...

A mathematics achievement test consisting of 100 questions was
given to 50 sixth grade students at maple Elementary School. The
following data show the number of questions answered correct by
each student.
75 48 46 65 71 49 61 51 57 49 84 85 79 85 83 55 69 88 89 55 61
72 64 67 61 77 51 61 68 54 63 94 54 53 71 84 79 75 65 50 45 65 77
71 63 67 57 63...

A college administrator is interested in knowing whether
a 3-week math mini-course affects a student's grade. Twenty
students are randomly selected and given a math test. These
students then attend the mini-course and are retested. Assume the
paired data come from a normal population for which the mean
difference is 0 Compute the value of the t-test statistic and
p-value for the paired data. At the 1% significance level,
determine whether the mini-course actually improves a student's
score.
Pre-course 68...

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...

5
The graph illustrates the distribution of test scores taken by
College Algebra students. The maximum possible score on the test
was 120, while the mean score was 78 and the standard deviation was
8.
546270788694102Distribution of Test Scores
What is the approximate percentage of students who scored less than
62 on the test?
%
What is the approximate percentage of students who scored between
70 and 78?
%
What is the approximate percentage of students who scored lower
than...

In a recent year, grade 6 Michigan State public school students
taking a mathematics assessment test had a mean score of 303.1 with
a standard deviation of 36. Possible test scores could range from 0
to 1000. Assume that the scores were normally distributed.
a. Find the probability that a student had a score higher than
295.
b. Find the probability that a student had a score between 230
and 305.
c. What is the highest score that would still...

Scores of an IQ test have a bell-shapped distribution
with a mean of 100 and standard deviation of 15. Use the empirical
rule to determine the following.
A.) What percentage of people has an IQ between 55 and
145?
B.) What percentage of people has an IQ score less than
85 or greater than 115?
C.) What percentage of people has an IQ score greater
than 145?
(Type an integer or decimal.)

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...

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