Hw3-sol

# Hw3-sol - H.W 3 Solutions 1 Sample average 19 xi x i 1 19 272.82 19 14.359 min Sample variance 19 xi i 1 19 272.82 xi2 10333.8964 i 1 n n 2 xi x 2

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H.W. # 3 Solutions 1. Sample average: min 359 . 14 19 82 . 272 19 19 1 = = = = i i x x Sample variance: ( 29 2 2 2 1 1 2 2 19 1 2 19 1 (min) 47 . 356 18 49 . 6416 1 19 19 82 . 272 8964 . 10333 1 8964 . 10333 82 . 272 = = - - = - - = = = = = = = n n x x s x x n i i n i i i i i i Sample standard deviation: min 88 . 18 47 . 356 = = s The sample standard deviation could also be found using ( 29 s x x n i i n = - - = 2 1 1 where ( 29 49 . 6416 19 1 2 = - = i i x x

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2. a.) Sample average: mm n x x n i i 173 . 2 9 56 . 19 1 = = = = b.) Sample variance: ( 29 2 2 2 1 1 2 2 9 1 2 9 1 ) ( 4303 . 0 8 443 . 3 1 9 9 56 . 19 953 . 45 1 953 . 45 56 . 19 mm n n x x s x x n i i n i i i i i i = = - - = - - = = = = = = = Sample standard deviation: mm s 6560 . 0 4303 . 0 = = c.) Dot Diagram . . . . . . . .. -------+---------+---------+---------+---------+---------crack length 1.40 1.75 2.10 2.45 2.80 3.15 3. a) 184 . 7 8 47 . 57 1 = = = = n x x n i i b) ( 29 000427 . 0 7 00299 . 0 1 8 8 47 . 57 853 . 412 1 2 2 1 1 2 2 = = - - = - - = = = n n x x s n i i n i i 02066 . 0 000427 . 0 = = s c) Examples: repeatability of the test equipment, time lag between samples, during which the pH of the solution could change, and operator skill in drawing the sample or using the instrument.
4. Stem-and-leaf of concentration N = 60 Leaf Unit = 1.0 2|2 represents 29 Note: Minitab has dropped the value to the right of the decimal to make this display. 1

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## This note was uploaded on 04/08/2008 for the course STAT 122 taught by Professor Elkamel during the Spring '08 term at Waterloo.

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Hw3-sol - H.W 3 Solutions 1 Sample average 19 xi x i 1 19 272.82 19 14.359 min Sample variance 19 xi i 1 19 272.82 xi2 10333.8964 i 1 n n 2 xi x 2

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