STAT 101 SEU Random Variable Questions

A Binomial random variable has a mean equal to 5 and a standard deviation of 2. So, theprobability of success in single trial, p = 0.8
True
False
The length of time of a particular phone call is an example of continuous random variable.
True
False
The Expected value of the random variable X where its values are 2, 3, 4 and the corresponding
probabilities are 0.3, 0.3, 0.4 respectively, is equal to
5.1
3.1
4.1
2.1
A company is studying the number of monthly absences among its 100 employees. The
following probability distribution shows the likelihood that people were absent 0, 1, 2, 3 or 4
days last month:
No. of days absent
0
1
2
3
4
Probability
0.50
0.10
0.20
0.20
0.00
What is the mean number of days an employee has been absent?
0.40
0.60
1.00
1.10
The random variable X has the following probability distribution.
x
0
1
2
3
P(x)
0.2
0.3
k
0.4
The value of k is
0
0.01
0.1
1.0
The following is a frequency distribution table for the kids ages in a nursery:
Age (Months)
0 – 11
12 – 23
24 – 35
Midpoint Frequency
9
5.5
17
17.5
14
29.5
The mean kids’ age in this nursery is 13.33.
True
False
The following are the grades of 20 students in STAT101. The percentile of the grade 90 is 80
54
60
60
62
66
67
68
69
70
73
74
74
77
82
84
88
90
91
95
97
True
False
Speed of train is an example of
Continuous Data
Discrete Data
Categorical Data
Qualitative Data
If A and B are mutually exclusive events, then
P(A or B) = 0
P(A or B) = P(A).P(B)
P(A or B) = P(A)/P(B)
P(A or B) = P(A) + P(B)
A survey of a sample of undergraduate students in the faculty of Science in a university revealed
the following regarding the gender and majors of the students:
Gender
Total
Major
Statistics
Physics
Mathematics
Male
20
12
8
40
Female
2
6
2
10
Total
22
18
10
50
A student is randomly selected, the probability of selecting a physics major, given that the
student selected is Female is equal to
6/50
6/10
10/40
8/40
The probability of drawing any one spade card from a pack of 52 cards is
4/13
1/4
1/13
1/52
If the relative frequencies of class-intervals of a distribution are 0.20, 0.10, x, 0.25 & 0.15. Then
the value of the missing value x is
0.15
0.20
0.25
0.30
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Question 13 of 25
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Question 13
The frequency distribution for a certain data is given from the following table
Class Interval
Frequency
50-59
2
60-69
7
70-79
5
80-89
6
90-99
5
Then the percentage frequency for the class 90-99 is:
30%
28%
20%
25%
Given the following frequency distribution:
Class Boundaries (Ages)
14.5-19.5
19.5-24.5
24.5-29.5
29.5-34.5
Frequencies (No. of Students)
4
8
14
14
Number of students whose age is more than 24.5 is equal to
12
14
26
28
The frequency distribution below summarizes the home sale prices in the city of Summerhill for
the month of June. Determine the width of each class.
Sale price in thousand $
Frequency
10-19
3
20-29
5
30-39
4
40-49
9
10
9
11
12
In tossing of three coins at a time, the probability of getting exactly two Heads is 1/2.
True
False
A box contains 2 red, 3 black and 5 green balls. One ball is selected randomly. The probability
of obtaining black ball is 0.3.
True
False
A researcher takes a sample of 150 employees of a company, the average age of company’s
employees is an example of a parameter.
True
False
Census is the sub collection of members selected from a population.
True
False
At one college, GPA’s are normally distributed with a mean of 3 and a standard deviation of 1.
According to empirical rule, What percentage of students at the college have a GPA between 2
and 4?
84.13%
99.7%
95%
68%
A student had the following grades in the related courses:
Course
Mathematics
English language
PE
Weight
6
4
2
Grade
70
65
92
Given the weights of the courses, the weighted mean grade of the student is:
75.67
72
288
864
Listed below are the amounts of time (in months) that the employees of a restaurant have been
working at the restaurant. What is the median of this data?
22, 11, 55, 33, 99, 66
44 months
33 months
55 months
22 months
Let the maximum usual value of a data set is 150. If the mean of this set is 130, then the standard
deviation of the data set using Range rule of thumb is
15
10
20
5
Let the total frequency of a distribution is 50. If the relative frequency of a class of this
distribution is 0.20, then the frequency of that class is 1.
True
False
The frequency table for certain data is given in the following table:
Class
10-19
20-29
30-39
40-49
Frequency
5
6
5
7
The Relative frequency for the class 30-39 is 0.25
True
50-59
2
False