# Section B

Q7. (a) When is Median a better method of Central Tendency than Arithmetic Mean? (5marks) (b) Write about the 5 precautions of using Secondary Data? (3 marks) (c) “You should be very careful while designing a questionnaire”. Elaborate on the statement (2 marks)

Q8. (a) Write down any 5 methods of making a sample? Explain briefly any two methods? (5marks) (b) Two regression lines of a sample are X+6Y=6 and 3X+2Y=0 Find (I) The correlation coefficient (II) Mean of X and Y (iii) Standard deviation of X if the Standard deviation of Y is 25 (5marks) Q9. (a) The specifications for the production of an alloy call for 23.2 gm of copper. A sample of 10 analysis of product showed a mean copper content of 23.5gm with a standard deviation of 0.24gm. Can we conclude that at 0.05 significance levels that the product meets the required specifications? (5marks) (b) The following table shows the number divorces in thousands in United States for the years 1986-1995. Construct a (I) 3years moving average (II) 4years centered moving average YEAR| 1986| 1987| 1988| 1989| 1990| 1991| 1992| 1993| 1994| 1995| NO. OF DIVORCES| 42| 55| 70| 68| 79| 82| 67| 72| 59| 87|

(5marks) Q10. (a) A Cellular phone company conducts a survey to determine the ownership of cellular phones in different age groups. The results for 1000 households are shown in the following table. Test the hypothesis that the proportions owning cellular phones are the same for the different age groups using Chi square distribution? Phone\ Age Groups| 18-24| 25-54| 55-64| >65| Total| Yes| 50| 80| 70| 50| 250|

No| 200| 170| 180| 200| 750|

Total| 250| 250| 250| 250| 1000|...

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