STAT 571 Midterm: STAT 571 UW Madison Fall 02Mid1 Solutions
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1. (a) the display appears skewed. (b) mean x = 21. 007. We can see this because 50% of data is be- tween 19. 5 and 21. 8 (inside the box). 2. (a) since v 2 = 27s2/49 2. 27, (c) np = 75 0. 4 > 5 and n(1 p) = 75 0. 6 > 5. (a) let y = the number of trees that are damaged. = 0. 296. (b) let xa be the number of trees sampled from plantation a that are damaged. P (s2 > 90) = p (v 2 > From table b, 0. 005 < p (v 2 > 49. 59) < 0. 01. (b) the statement is true. As the sample size increases, s2 becomes a better estimate of 2. More speci cally, the distribu- tion of s2 becomes more tightly centered on. 2 = 49, and so p (s > 90) becomes smaller. 3. (a) since x n (68, 900), = p (z > 0. 07) p (z > 0. 73)
