Question

1. Public health officials interested in determining the monthly mean rate of suicides in western Massachusetts gathered information over a 5-year period. The following table gives the frequency distribution of the number of cases reported each month:

Number of Cases, x	0	1	2	3	4	5	6	7	Total
Number of months	1	7	19	11	9	6	4	3	60

Construct a 95% confidence interval for the population monthly mean rate. (Hint: The number of cases of suicide in a month follows a Poisson distribution.) You will need to find the weighted average number of suicides per month over the 60 months (not over the 8 possible values).

Answer 1

First we need to find the mean and SD of data set. Following table shows the calculations:

	X	frequency, f	fx	f(X-mean)^2
	0	1	0	9.9225
	1	7	7	32.3575
	2	19	38	25.1275
	3	11	33	0.2475
	4	9	36	6.5025
	5	6	30	20.535
	6	4	24	32.49
	7	3	21	44.4675
Total		60	189	171.65

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