Statıstıcs I Final 6. Deneme Sınavı
Toplam 20 Soru1.Soru
Which level of measurement is not suitable for Median
Continuous |
Discrete |
Interval |
Nominal |
Ratio |
2.Soru
Which class interval is containing the median?
0 up to 20 |
20 up to 40 |
40 up to 60 |
60 up to 80 |
80 up to 100 |
To determine the interval that contains the median, we must find the first interval for which the cumulative relative frequency exceeds 0.50. This interval is the one containing the median. For the following data, the interval from 40 up to 60 is the first interval for which the cumulative relative frequency exceeds 0.50, so this interval contains the median.
3.Soru
Which of the followings are not correct related to probability density function?
In order to calculate the area under a probability function between two points by utilizing probability density function, f (x). |
The probability density function f (x), defines the physical characteristics of the random variable. |
The probability density function determines the shape of the distribution for the continuous random variable X. |
The area under the probability density function f (x) is always equivalent to 3. |
Probability density function is represented by f (x). |
Because of the probability density function must satisfy the rule: ∫∞ f(x)dx=1,
the area under the probability density function f (x) is always equivalent to 1
4.Soru
The above table contains the daily sales data of a market. We want to construct relative frequency distribution table for the data. What is the first class’ relative frequency?
0,32 |
0,47 |
0,53 |
0,60 |
0,64 |
5.Soru
Which statements below are correct?
I Exponential distribution is a type of a discrete random variable.
II Discrete random variables have only a countable number of distinct values.
III A discrete random variable typically comprises of a counting concept.
IV Continuous random variables represent entire infinite values in an interval.
V Continuous random variables are commonly measured instead of counted.
I, II, III, IV |
I, II, III, V |
II, III, IV, V |
I, III, IV, V |
Only I |
As it can be recalled that discrete random variables have only a countable number of distinct values such as 0, 1, 2, 3... etc. In other words, a discrete random variable typically comprises of a counting concept. On the other hand, continuous random variables represent entire infinite values in an interval. For that reason, continuous random variables are commonly measured instead of counted. The speed of a plane, waiting time of customers at a bank’s call center, rainfall amount in a given day and inter arrival time between two customers which arrive to the post office are commonly cited examples for continuous random variables.
6.Soru
X=x | 1 | 2 | 3 | 4 |
P(X=x) | 0,20 | 0,30 | 0,30 | 0,20 |
Which of the following is the standard deviation of the given data above?
1.9 |
1.95 |
2 |
2.015 |
2.0615 |
?= 2.0615
7.Soru
Which of the following is a measure of the midpoint or center of the probability distribution?
Mean |
Median |
Mode |
Variance |
Range |
Similar to the discrete random variable the mean is a measure of the midpoint or center of the probability distribution.
8.Soru
The above table contains the daily sales data of a market. We want to construct grouped frequency distribution table for the data. What is the class width of the data?
80 |
90 |
100 |
110 |
120 |
The first step in constructing the grouped frequency distribution table is to determine the number of classes.
9.Soru
Assume that 20 percent of Statistics course students in Anadolu University take Music course, 10 percent take Swimming course, and 4 percent take both Music and Swimming courses. What percentage of Statistics students neither take Music nor Swimming course?
80 |
74 |
70 |
66 |
34 |
(S and M) = 20 % ; (S ansd Sw) : 10 % ; (S and M and Sw) = 4 % ; (S and (M or Sw)) = 26 % , (S and NOT(M and Sw) )= 100 – 26 = 74 % . pg. 138. Correct answer is B.
10.Soru
During a sales season, the fifteen salesmen in a computer company sold the following numbers of computers: 7, 11, 5, 12, 17, 6, 13, 9, 8, 4, 23, 12, 7, 6, 11.
Which of followings is the range of the number of sold computers?
During a sales season, the fifteen salesmen in a computer company sold the following numbers of computers: 7, 11, 5, 12, 17, 6, 13, 9, 8, 4, 23, 12, 7, 6, 11.
Which of followings is the range of the number of sold computers?
R = 23 - 4 = 19 |
R = 4 - 23 = 19 |
R = 19 - 7 = 23 |
R = 11 - 5 = 19 |
R = 12 - 8 = 23 |
The range for grouped frequency distribution is calculated to be the difference of the upper limit of the highest class and the lower limit of the first class. Therefore, it will be an approximate value.
11.Soru
A engineer wants to choose the best company to work for. Before choosing the company, he classifies the companies according to their location and salary offered. There are 12 different locations and 10 different salaries. In how many different ways can companies be classified?
A engineer wants to choose the best company to work for. Before choosing the company, he classifies the companies according to their location and salary offered. There are 12 different locations and 10 different salaries. In how many different ways can companies be classified?
22 |
220 |
2200 |
120 |
1200 |
Consider any two experiments of which the first experiment can result in n1 and the second can result in n2 possible outcomes. Then, considering both experiments together, there are n1n2 possible outcomes. This principle can also be generalized to a finite number of experiments.
According to the basic principle of counting, it follows that there are in total 10.12=120 different possible classifications.
12.Soru
If one wants to model the number of customers entering to a fast food restaurant per hour, which probability distribution should he/she use?
Poisson |
Binomial |
Hypergeometric |
Continious |
Bernoulli |
13.Soru
Which one is frequently used to summarize the features of probability distributions for a discrete random variable X?
Hypergeometric distribution |
Binomial distribution |
Arithmetic mean and variance |
Probability distribution |
Cumulative distribution |
Arithmetic mean and variance are frequently used to summarize the features of probability distributions for a discrete random variable X .So the correct answer is C
14.Soru
The probability of an event A is 0.6, the probability of an event B is 0.3. The probability that neither A nor B occurs is 0.25. What is the probability that both A and B occurs?
0.35 |
0.30 |
0.25 |
0.20 |
0.15 |
P(A or B) = 1 – 0.25 = 0.75 P(A and B) = P(A) + P(B) – 0.75 = 0..6 + 0.3 – 0.75 = 0.15 . pg. 138. Correct answer is E.
15.Soru
Which of the followings is the most important and widely used measure of variability in statistics ?
Range |
Percentiles |
Standard Deviation |
Interquartile Range |
Variance |
In order to avoid the disadvantages of the range, we need a measure of variability that is based on including all measurements in a data set. The most important and widely used measure of variability in statistics is the standard deviation.
16.Soru
Which one is a widely employed discrete probability distribution in statistics where a set of independent observations constitutes exactly two disjoint outcomes of a trial?
Hypergeometric distribution |
Binomial distribution |
Poisson distribution |
Probability distribution |
Cumulative distribution |
Binomial distribution is a widely employed discrete probability distribution in statistics where a set of independent observations constitutes exactly two disjoint outcomes of a trial.So the correct answer is B.
17.Soru
The box plot is given above shows the data about the number of hours spent on watching tv a day by students in a school.
Which of the following is not correct about the box plot data?
The median is two hours. |
The interquartile range is three hours. |
50% of the people watch three hours of TV a day. |
The shape of the distribution is left-skewed. |
There are outliers in the data. |
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.
18.Soru
Let's assume that three perfect coins are flipped three times, what is the probability that all the results are head?
2/9 |
3/8 |
2/4 |
1/8 |
1/16 |
The sample space is
S = {(TTT), (TTH), (THT), (HTT), (THH), (HTH), (HHT), (HHH)}
only once all the results are head, therefore
P(all head) = 1/ 8
19.Soru
A manager of a café in a university campus assesses its customers as student, academic staff or visitor. She estimates that of all its customers 50% are students, 30% are academic staff and that 20% are visitors. It is known that purchases are made by 70% of student customers, by 60% of academic staff and by 30% of visitors. If a randomly chosen customer makes a purchase, what is the probability that this customer is a student?
0,74 |
0,54 |
0,59 |
0,95 |
0,059 |
Define the following events
S: Customer is a student
A: Customer is academic staff
V: Customer is a visitor
B: Customer makes a purchase
Then we need to find P(S?B), which is given by, P(S?B)=P(B?S)P(S)/P(B?S)P(S)+ P(B?A) P(A)+ P(B?V)P(V) = 0.35/0.59 ? 0.593
20.Soru
A company works with two supplier firms for the same raw material. The first firm's late delivery probability on a given day is 0.05, whereas for the second firm this probability is 0.07. In addition, both firms' late delivery probability on given day is 0.04. What is the late delivery probability of at least one of the firms to company on given day?
0.05 |
0.06 |
0.07 |
0.08 |
0.09 |
P(OUY) = P(O) + P(Y) - P(O∩Y) = 0.05 + 0.07 - 0.04 = 0.08
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