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TWO MARKS. What are the common types of variables used in statistics? 1. Discrete random variables Eg: X = 0,1,2,3 2. Continuous random variables Eg: 3 ≤ X ≤ 6. Name a few descriptive measures of data. Mean Median Mode Quartiles Deciles Percentiles.
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TWO MARKS • What are the common types of variables used in statistics? • 1. Discrete random variables • Eg: X = 0,1,2,3 • 2. Continuous random variables • Eg: 3 ≤ X ≤ 6
Name a few descriptive measures of data • Mean • Median • Mode • Quartiles • Deciles • Percentiles
What are the elements and variables in a data set? • Elements: • Qualitative Data, Quantitative Data, Chronological and Geographical Data • Variables : 1. Discrete random variables • Eg: X = 0,1,2,3 2. Continuous random variables • Eg: 3 ≤ X ≤ 6
Distinguish between qualitative and quantitative variables in statistics. • Quantitative Variables: • These are the variables which are measurable in nature such as age, income, height etc. • Qualitative Variables: • These are the variables which are non-measurable quality characteristics such as sex, honesty, literacy, blindness etc. It is sometimes called Attributes
What are the sources of collecting data? • Primary source • Secondary source
Give the mathematical definition of probability. • Probability is the chance of getting an event in an experiment. • Mathematically, probability is defined as Total no. of Favourable Cases n(E) P(E) = ------------------------------------------- = ------ Total no. of Possible Cases n(S)
Define Binomial Distribution. • A discrete random variable X is said to follow Binomial distribution if its probability mass function is defined as P(X=x) = nCx px qn-x ; x = 0, 1, 2, 3, . . .n where n – no. of trials x – no. of successes p – probability of success q – probability of failures
Define Poisson Distribution • A discrete random variable is said to follow Poisson distribution if its probability mass function is given by e-λλx P(X=x) = ----------- ; x = o,1,2,3,….∞ x!
Give two examples of Poisson distribution • No. of air accidents in a particular aircraft • No. of deaths due to specific disease • No. of defective pieces in a batch of lots
Write any two properties of Normal distribution • Mean = Median = Mode • Coefficient of skewness = 0 • Normal curve is symmetric one • It is a unimodal distribution
The following information regarding the top ten Fortune 500 companies was presented in an issue of Fortune Magazine
How many elements are in the above data set? • How many variables are in this data set? • How many observations are in this data set? • Which variables are qualitative and which are quantitative? • What measurements scale is used for each variable?
The following data shows the yearly income distribution of a sample of 200 employees at MNM. Inc.
(i) What percentage of employees has yearly income of $35,000 or more? • (ii) Is the figure(percentage) that you computed in (i) an example of statistical inference? If no, what kind of statistics does it represent? • (iii) Based on this sample the president of the company’s aid that 45% of all our employees yearly income are $35,000 or more. The president’s statement represents what kind of statistics? • (iv) With the statement made in (iii) can we assure that more than 45% of all employees yearly income are atleast $35,000? Explain
(v) What percentage of employees of the sample has yearly income of $29,000 or less? • (vi) How many variables are presented in the above data set? • (vii) The above data set represents the results of how many observations?