STAtistics / Mr. Hansen	Name: _______________________________________
	HW due 2/16/2012

Family Vacation Exercise (Excerpt from Chapter 9 Test)

• Calculator is OK throughout.
• If a blank is provided, give the short answer that fits best. Work is not required in such a situation.
• If a gap is provided, provide adequate justification/explanation, and circle your answer.

5.(a)	The randInt(0,9) command has been employed to generate 40 random integers between 0 and 9, inclusive. These data are listed below. Make a dotplot or a stemplot (your choice) of the data. (A dotplot is identical to a histogram, except using dots for the data points instead of bars.)
	9, 2, 3, 7, 9, 0, 4, 8, 5, 6, 0, 1, 0, 8, 9, 4, 3, 3, 8, 3, 2, 4, 3, 8, 2, 2, 1, 6, 5, 4, 9, 2, 5, 2, 5, 6, 6, 5, 2, 0
(b)	The distribution of data is approximately (circle one) normal t-shaped  binomial  uniform.
(c)	Compute the sample mean and sample s.d., using correct symbols to label your results.
	sample mean = ____ = _____________
	sample s.d. = ____ = _____________
(d)	The sampling distribution of when n = 40 is (circle one) normal t-shaped  binomial  uniform.
(e)	Compute the exact value of (assuming truly random data from 0 to 9) and the approximate value of . No work is expected.
	= ______________
	______________

(f)

Suppose that you were handed the data set above, with n = 40, but were told only that the range was 9 and that the values denoted the number of family vacations that various families had taken in the previous 9 years, and that the data were from an SRS of Bethesda families. Use your values from part (c) to compute a 90% confidence interval for the true mean. Check assumptions and give conclusion in context. Work is optional.

(g)

Approximately how many families would we need to survey in order to obtain an m.o.e. of 0.5 or less? Explain your work well enough that it would make sense to a reader. Don’t simply make random scratch work. An exact answer is not expected.