Statıstıcs I Final 11. Deneme Sınavı
Toplam 20 Soru1.Soru
Which of the following statements is not true regarding "percentiles"?
The percentiles generally are demonstrated as P(m), where m is the number taking values between 0 and 100. |
Intuitively, the P(m) percentile of a set of n measurements, arranged in order of magnitude, is the value such m percent of the measurements are less than or equal to that corresponding value. |
Some of the specific percentiles frequently used as variability measures are 25th, 50th, and 75th percentiles. |
Various methods may be used for the calculation of percentiles. |
In order to calculate the percentiles, the sample measurements must be sorted from largest to smallest. |
In order to calculate the percentiles, the sample measurements must be sorted in ascending order (from smallest to largest).
2.Soru
What do we call, If a data set has two modes?
Median |
Bimodal |
TripleModal |
Nominal mode |
Minimum mode |
If a data set has more than one mode, it refers to a multimodal distribution, indicating the frequencies of several observations with the similar highest frequencies. Specifically, when two values have the highest frequency in the data as in 1, 2, 2, 3, 4, 4, 5, 6, it is called as bimodal (2 and 4) distribution.
3.Soru
Study the following discrete probability distribution:
According to table what is the probability that the result is equal to 2 or less?
3/8 |
1/8 |
2/8 |
7/8 |
8/8 |
the result is the total of the following probabilities:
1/8 + 3/8 + 3/8 = 7/8
4.Soru
The height of the students in a class as follows;
155, 156, 157, 160, 162, 165, 170, 180.
Which of the following is the median of the given data?
160 |
161 |
162 |
163 |
164 |
155 + 156 + 157 + 160 + 162 + 165 + 170 + 180 / 9= 161
5.Soru
I. The number of people in a mall. II. The speed of a car. III. The exam points of students in a class. Which of the variables above continuous random variable?
I |
I and II |
I, II, and III |
II and III |
III |
The number of people in a mall can be countable while the other variables are measured.
6.Soru
Data : 20, 12, 16, 12, 10 ; what is the standard coefficient of skewness of these data ?
55 / 32 |
65 / 34 |
75 / 42 |
85 / 44 |
95 / 48 |
a = 5 / (4 x 3) = 5 / 12 ; arithmetic mean : m = 70 / 5 = 14 ; s = ((42 + 22 + 22 + 22 + 62) / 4)1/2 = 4 ; standard coefficient of skewness SCS = (5 / 12) x ((43 + 23 + 23 + 23 + 63) / 43) = (5 / 12) ((64 + 24 + 216) / 64) = (5 / 12) (304 / 64) = (5 / 12) (76 / 16) = (5 / 12) (19 / 4) = 95 / 48. pg. 122. Correct answer is E.
7.Soru
Which of the followings is the differences between the third and the first quartiles?
Which of the followings is the differences between the third and the first quartiles?
Percentiles |
Range |
Interquartile Range |
Box Plot |
Skewness |
The second variability measure is the interquartile range (IQR). The interquartile range is the differences between the third and the first quartiles.
8.Soru
According to empirical probability approach, what is the probability of obtaining a number 6 when you throw a six-sided fair die?
0.172 |
0.272 |
0.372 |
0.472 |
0.572 |
According to empirical probability approach, what is the probability of obtaining a number 6 when you throw a six-sided fair die? Using the formula given before the probability we are looking for is:
P(Number 6) = 172/ 1000= 0.172
The correct answer is A.
9.Soru
The number of houses sold by each of the 10 estate agents during a particular 6 months period are 1, 4, 7, 6, 2, 10, 10, 3, 8, 9. What is the range of the data?
10 |
9 |
5 |
3 |
1 |
The range of a data set, shown as R, is the difference between the largest and smallest values and calculated as follows: R = Largest Value - Smallest Value
R = 10-1 = 9. The correct answer is B.
10.Soru
Which of the followings is not true about cumulative distribution function?
Cumulative distribution function defined as F(x)=P(X≤x)= ∫x f(t)dt,−∞<x<∞. |
The cumulative distribution function probability supplies values by utilizing probability density function. |
Cumulative distribution function f(x) of a continuous random variable X fulfils the following property; f(x)≥0 for all x. |
Cumulative distribution function f(x) of a continuous random variable X fulfils the following property; if x1 ≤ x2 then F (x1) ≤ F (x2). |
Cumulative distribution function f(x) of a continuous random variable X fulfils the following property; 0 ≤ F (x) ≤ 1. |
Not cumulative distribution function but probability density function fulfils the property of f(x)≥0 for all x.
11.Soru
Which of the following is not variable?
depth |
darkness |
noise |
sense |
feeling |
darkness is data, not variable. pg. 14. Correct answer is B.
12.Soru
Find out the mean score of the following data set: 10,20,40,60,100?
42 |
43 |
44 |
45 |
46 |
The answer is E)46 as : The total scores are 230 and when we divide 230 by 5 we get 46
13.Soru
Data : 1.000, 1.000, 1.200, 1.200, 1.200, 1.400, 1.400, 1.500, 1.500, 1.500, 1.600, 1.600, 1.800, 1.800, 1.800, 2.000, 2.000, 2.500, 2.500, 2.500. What is the IQR of these data ?
500 |
600 |
700 |
800 |
900 |
The interquartile range IQR = P(75) – P(25) ; k1 = 20 x (75 / 100) = 15 ; P(75) = (1.800 + 2.000) / 2 = 1.900 ; k2 = 20 x (25 / 100) = 5 ; P(25) = (1.200 + 1.400) / 2 = 1.300 ; IQR = 1.900 – 1.300 = 600 . pg. 120. Correct answer is B.
14.Soru
What is the mean of f(x) = x for 0 ? x ? 4 equal to?
8 |
9 |
10 |
11 |
12 |
The mean of an f(x) function is equal to the integral of that function's product to it's respective x on the given range. For the function f(x)= x for 0 ? x ? 3 the integral of x*f(x) on the range 0 to 4 is taken. This would yield to the integral of x2 which is equal to x3/3. For x=0 this would equal to 0, for x=4 this would equal to 9. The mean is equal to 9 - 0 = 9. The answer is B.
15.Soru
What type of a graphic is used to investigate the relationship between two variables?
Dot plot |
Pie chart |
Histogram |
Scatter plot |
Line chart |
Scatter plot is used to investigate the relationship between two variables. They are also very helpful indicating the minimum, maximum or outliers of the variables.The correct answer is D.
16.Soru
During a sales season, the five salesmen in a mobile phone company sold the following numbers of mobile phone: 9, 15, 8, 24, 30. What is the range of the number of sold mobile phones?
22 |
21 |
15 |
9 |
6 |
The range for grouped frequency distribution is calculated to be the difference of the upper limit of the highest value and the lower limit of the first class.
R=30-8=22
17.Soru
I. f (x) ? 0 for all x.
II. the area under probability density function between points a and b is equal to 1
III. P(a ? X ? b) is equal to 1
Which of the statements should the probability density function satisfy?
Only I |
Only II |
I and II |
I and III |
II and III |
For a continuous random variable X, probability density function f (x) must satisfy the following
properties,
(i) f (x) ? 0 for all x,
(ii) the integral of f(x) between positive infinite and negative infinite is equal to 1
(iii) P(a ? X ? b) is equal to the area under probability density function between points a and b.
The answer is A.
18.Soru
Which of the following statements is true according to the box-plot given below?
The median is 4 cigarettes. |
The interquartile range is 2 cigarettes. |
The shape of the distribution is right-skewed. |
The values greater than 4 are the outliers. |
50% of the workers consume less than 4 cigarettes. |
The median is 2 cigarettes. This means that 50% of the workers consume less than 2 cigarettes, and 50% of the workers consume more than 2 cigarettes. The 25th and 75th percentiles are 1 and 4 cigarettes, respectively. This means that 25% of the workers consume is either less than or equal to 1 cigarettes and 75% of the workers consume leither 4 or fewer than 4 cigarettes a day. The interquartile range is 4-1=3 cigarettes. This means that 50% of the workers consume 3 cigarettes. The highest and the lowest values within the upper and the lower boundaries for outliers are 8 and 0, respectively. There are outliers in the data. The values greater than 8 are the outliers. The shape of the distribution is right skewed, because the median line is closer to the 25th percentile and also the whisker over the 75th percentile is longer than the other whisker.The correct answer is C.
19.Soru
Which of the following can be estimated by using ogive curve?
Mode |
Arithmetic mean |
Median |
Geometric mean |
Trimmed mean |
The median can also be estimated by using ogive curve (cumulative frequency polygon). The correct answer is C.
20.Soru
Which one can be defined as a rule that assigns probabilities to the values of random variables?
Hypergeometric distribution |
Binomial distribution |
Poisson distribution |
Probability distribution |
Cumulative distribution |
We can define probability distribution as a rule that assigns probabilities to the values of random variables.So the correct answer is D.
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