2017 (May–June)
COMMERCE (Speciality)
Paper: 304 (Business Statistics)
Full Marks: 80
Time: 3 Hours
The figures in the margin indicate full marks for the questions
1. (a) Fill in the blanks:
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If A is an event then ____ ≤ P(A) ≤ ____.
The aggregate of all sample points is called the ____.
The independent variable values in interpolation are termed as ____.
Cost of Living Index Numbers are known as ____.
(b) Write down the approximate relation between mean, median and mode of a moderately skewed distribution.
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(c) Find the SD of the values given below: 2, 2, 2, 6, 6, 6.
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(d) If the mean of the series X₁, X₂, …, Xₙ is X̄, what is the mean of the series 4X₁, 4X₂, …, 4Xₙ?
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(e) Mention the parameter of Poisson probability distribution.
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(f) Mention two control charts for variables in SQC.
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(g) Select the correct answer:
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If r = ±1, the two lines of regression are:
Coincident
Parallel
Perpendicular to each other
None of the above
2. (a) Find the GM of 0.2 and 3.2.
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(b) Distinguish between parameter and statistic.
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(c) Find E(X) for the following probability distribution of X:
| X | 0 | 1 | 2 | 3 |
|---|---|---|---|---|
| P | 1/8 | 3/8 | 3/8 | 1/8 |
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(d) State two essential points to be noted while drafting a questionnaire.
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(e) Mention two properties of correlation coefficient.
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3. Answer any four of the following questions: 5×4=20
(a) Distinguish between primary data and secondary data. Mention various methods of collecting primary data.
(b) Write a note on the importance of Statistics in Commerce.
(c) Define mathematical expectation. A random variable X has the following probability distribution:
| X | 1 | 2 | 3 | 4 | 5 | 6 |
|---|---|---|---|---|---|---|
| P(X) | 1/6 | 1/6 | 1/6 | 1/6 | 1/6 | 1/6 |
Find E(X) and Var(X).
(d) Of a certain distribution, the Karl Pearson’s coefficient of Skewness is 0.4, the standard deviation is 8 and mean is 30. Find the mode and the median of the distribution.
(e) Mention the chief characteristics of normal probability distribution.
(f) What is a control chart? Explain the reason for 3σ control limits for a control chart.
4. (a) Calculate mean and coefficient of variation from the following data: 2+4=6
| Marks | 0–10 | 10–20 | 20–30 | 30–40 | 40–50 |
|-------|------|-------|-------|-------|
| No. of students | 5 | 15 | 25 | 10 | 5 |
(b) Define dispersion. Distinguish clearly between absolute and relative measures of dispersion. 1+3=4
5. (a) A problem in statistics is given to five students A, B, C, D, and E. Their respective chances (probability) of solving it are 1/2, 1/3, 1/4, 1/4 and 1/5 respectively. What is the probability that at least one of the students solve the problem?
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(b) If 5% electric bulbs manufactured by a company are defective, find the probability that in a sample of 100 bulbs:
5+1=6
None are defective
3 bulbs are defective
6. (a) Fit a straight line trend by the method of least square to the following data: 5+1=6
| Year | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 |
|------|------|------|------|------|------|------|
| Production (Rs. crores) | 7 | 10 | 12 | 14 | 17 | 20 | 24 |
Estimate the likely production for 2016.
(b) Write a note on usefulness of Index Number.
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7. (a) Discuss the relative advantages and limitations of sample survey and census survey.
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(b) Explain the concepts of Type I and Type II Error.
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8. (a) The following data are given: 5+1=6
| | X | Y |
|---|---|---|
| Mean | 40 | 6 |
| S.D. | 10 | 1.5 |
Correlation coefficient between x and y = 0.9
Find the two regression equations
Estimate the value of y when x = 60
(b) Distinguish between interpolation and extrapolation giving examples.
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9. (a) Estimate by Newton’s method of interpolation, the expectation of life at the age 12 years from the following data:
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| Age | 10 | 15 | 20 | 25 | 30 | 35 |
|------|-----|-----|-----|-----|-----|-----|
| Years | 35.4 | 32.3 | 29.2 | 26.0 | 23.2 | 20.4 |
(b) What do you mean by correlation between two variables? Explain different types of correlation.
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10. (a) What are assignable and chance causes of variation in a manufacturing process? When is manufacturing process said to be under statistical quality control?
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(b) Write short notes on any two: 3×2=6
Test of hypothesis
Kurtosis
Level of significance
-0000-
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