Practice Questions On Probability Distribution, Standard Deviation and Percentile
Question
Consider probability distribution as standard normal, if value of µ is 75, value of x is 120 with unknown standard deviation of distribution then value of z-statistic
Answer
will be positive
Question
If value of x for normal distribution is 35, mean of normal distribution is 65 and standard deviation is 25 then standardized random variable is
Answer
-1.2
Question
In binomial distribution, formula of calculating standard deviation is
Answer
square root of npq
Question
In a given sports activity, the annual rate of accidents is of about 4 per thousand people. An insurance company has 3000 insured clients that practice such sports activity. A good approximation of the number of accident compensations the insurance company will have to pay in a given year is given by the distribution
Answer
Poisson (lambda = 12)
Question
The number of clients that enter a given store each hour follows a Poisson distribution with mean 3.25. We assume independence between the di?erent hours. The probability that in a given hour exactly 5 clients enter the store is?
Answer
0.1172
Question
Data based on workers salary is given as: 2500, 2700, 2600, 2800, 2200, 2100, 2000, 2900, 3000, 2800, 2200, 2500, 2700, 2800, 2600; and number of classes desired is 10 then width of class interval is
Answer
100
Question
If a value represents the 95th percentile, this means:
Answer
95% of all values are below this point
Question
Suppose that a histogram of a data set is approximately symmetric and “bell shaped”. Approximately _____ percent of the observations are within one standard deviation of the mean
Answer
68
Question
If quartile range is 24 then quartile deviation is
Answer
48
Question
if ({}^{n}textrm{C}_{12}={}^{n}textrm{C}_{6}), the value of n is
Answer
18
Question
There are 6 pupils and 4 cats. In how many can they be seated in a row so that no cats sit together
Answer
6! × 7P4
Question
The probability of success changes from trial to trial in
Answer
Hypergeometric Distribution
Question
Hypergeometric distribution has parameters
Answer
3
Question
In a survey of companies, it was found that 45 were in the mining sector, 72 were in the financial sector, 32 were in the IT sector and 110 were in the production sector. If a company is selected at random, what is the probability that this company is not in the production sector?
Answer
0.575
Question
If A and B are mutually exclusive events with P(A) = 0.3 and P(B) = 0.5, then (P(Acup B)) =
Answer
0.8
Question
If A and B are mutually exclusive events with P(A) = 0.3 and P(B) = 0.5, then (P (Acap B)) =
Answer
zero
Question
In a survey of companies, it was found that 45 were in the mining sector, 72 were in the financial sector, 32 were in the IT sector and 110 were in the production sector. What is the likelihood that a randomly selected company is either a mining company or an IT company
Answer
0.297
Question
Which of the following statements is always correct?
Answer
Median = Q2 = D5 = P50
Question
The mean of 10 observations is 10. All the observations are increased by 10%. The mean of increased observations will be:
Answer
11
Question
A researcher is interested in the travel time of Utrecht University students to college. A group of 50 students is interviewed. Their mean travel time in 16.7 minutes. For this study the mean of 16.7 minutes is an example of a(n) ___________
Answer
Statistic
Question
Consider probability distribution as standard normal, if value of µ is 75, value of x is 120 with unknown standard deviation of distribution then value of z-statistic
Answer
will be positive
Question
If value of x for normal distribution is 35, mean of normal distribution is 65 and standard deviation is 25 then standardized random variable is
Answer
-1.2
Question
In binomial distribution, formula of calculating standard deviation is
Answer
square root of npq
Question
In a given sports activity, the annual rate of accidents is of about 4 per thousand people. An insurance company has 3000 insured clients that practice such sports activity. A good approximation of the number of accident compensations the insurance company will have to pay in a given year is given by the distribution
Answer
Poisson (lambda = 12)
Question
The number of clients that enter a given store each hour follows a Poisson distribution with mean 3.25. We assume independence between the di?erent hours. The probability that in a given hour exactly 5 clients enter the store is?
Answer
0.1172
Question
Data based on workers salary is given as: 2500, 2700, 2600, 2800, 2200, 2100, 2000, 2900, 3000, 2800, 2200, 2500, 2700, 2800, 2600; and number of classes desired is 10 then width of class interval is
Answer
100
Question
If a value represents the 95th percentile, this means:
Answer
95% of all values are below this point
Question
Suppose that a histogram of a data set is approximately symmetric and “bell shaped”. Approximately _____ percent of the observations are within one standard deviation of the mean
Answer
68
Question
If quartile range is 24 then quartile deviation is
Answer
48
Question
if ({}^{n}textrm{C}_{12}={}^{n}textrm{C}_{6}), the value of n is
Answer
18
Question
There are 6 pupils and 4 cats. In how many can they be seated in a row so that no cats sit together
Answer
6! × 7P4
Question
The probability of success changes from trial to trial in
Answer
Hypergeometric Distribution
Question
Hypergeometric distribution has parameters
Answer
3
Question
In a survey of companies, it was found that 45 were in the mining sector, 72 were in the financial sector, 32 were in the IT sector and 110 were in the production sector. If a company is selected at random, what is the probability that this company is not in the production sector?
Answer
0.575
Question
If A and B are mutually exclusive events with P(A) = 0.3 and P(B) = 0.5, then (P(Acup B)) =
Answer
0.8
Question
If A and B are mutually exclusive events with P(A) = 0.3 and P(B) = 0.5, then (P (Acap B)) =
Answer
zero
Question
In a survey of companies, it was found that 45 were in the mining sector, 72 were in the financial sector, 32 were in the IT sector and 110 were in the production sector. What is the likelihood that a randomly selected company is either a mining company or an IT company
Answer
0.297
Question
Which of the following statements is always correct?
Answer
Median = Q2 = D5 = P50
Question
The mean of 10 observations is 10. All the observations are increased by 10%. The mean of increased observations will be:
Answer
11
Question
A researcher is interested in the travel time of Utrecht University students to college. A group of 50 students is interviewed. Their mean travel time in 16.7 minutes. For this study the mean of 16.7 minutes is an example of a(n) ___________
Answer
Statistic
