October 20, 2019

# 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