This set of Data Science Multiple Choice Questions & Answers (MCQs) focuses on “Probability and Statistics”.

1. The expected value or _______ of a random variable is the center of its distribution.

a) mode

b) median

c) mean

d) bayesian inference

View Answer

Explanation: A probability model connects the data to the population using assumptions.

2. Point out the correct statement:

a) Some cumulative distribution function F is non-decreasing and right-continuous

b) Every cumulative distribution function F is decreasing and right-continuous

c) Every cumulative distribution function F is increasing and left-continuous

d) None of the Mentioned

View Answer

Explanation: Every cumulative distribution function F is non-decreasing and right-continuous.

3. Which of the following of a random variable is a measure of spread ?

a) variance

b) standard deviation

c) empirical mean

d) all of the Mentioned

View Answer

Explanation: Densities with a higher variance are more spread out than densities with a lower variance.

4. The square root of the variance is called the ________ deviation.

a) empirical

b) mean

c) Continuous

d) standard

View Answer

Explanation: Standard Deviation (SD) is the measure of spread of the numbers in a set of data from its mean value.

5. Point out the wrong statement:

a) A percentile is simply a quantile with expressed as a percent

b) There are two types of random variable

c) R cannot approximate quantiles for you for common distributions

d) None of the Mentioned

View Answer

Explanation: R can approximate quantiles for you for common distributions.

6. Which of the following inequality is useful for interpreting variances ?

a) Chebyshev

b) Stautaory

c) Testory

d) All of the Mentioned

View Answer

Explanation: Chebyshev’s inequality is also spelled as Tchebysheff’s inequality.

7. For continuous random variables, the CDF is the derivative of the PDF

a) True

b) False

View Answer

Explanation: For continuous random variables, the PDF is the derivative of the CDF.

8. Chebyshev’s inequality states that the probability of a “Six Sigma” event is less than :

a) 10%

b) 20%

c) 30%

d) 3%

View Answer

Explanation: If a bell curve is assumed, the probability of a “six sigma” event is on the order of one ten millionth of a percent.

9. Which of the following random variables are the default model for random samples ?

a) iid

b) id

c) pmd

d) all of the Mentioned

View Answer

Explanation: Random variables are said to be iid if they are independent and identically distributed.

10. Cumulative distribution functions are used to specify the distribution of multivariate random variables.

a) True

b) False

View Answer

Explanation: In the case of a continuous distribution, it gives the area under the probability density function from minus infinity to x.

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