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Unformatted text preview: 1 Homework from Section 5.4 5.27 (p.221). A chemical supply company currently has in stock 100 pounds of a certain chemical, which it sells to its customers in 5lb lots. Let x denote the number of lots ordered by a randomly selected customer, and supposed x has the following probability mass function: x: 1 2 3 4 p(x) 0.2 0.4 0.3 0.1 a) Compute the mean number of lots ordered by a customer. = ∙ ( ) =1 = 1 ¡ 0.2 ¢ + 2 ¡ 0.4 ¢ + 3 ¡ 0.3 ¢ + 4 ¡ 0.1 ¢ = 2.3 b) Compute the variance of the number of lots ordered by a customer. 2 = ¡ − ¢ 2 ∙ ( ) = ¡ 1 − 2.3 ¢ 2 ¡ 0.2 ¢ + ¡ 2 − 2.3 ¢ 2 ¡ 0.4 ¢ + ¡ 3 − 2.3 ¢ 2 ¡ 0.3 ¢ + ¡ 4 − 2.3 ¢ 2 ¡ 0.1 ¢ = 0.338 + 0.036 + 0.147 + 0.289 = 0.810 c) Compute the expected number of pounds left after a customer’s order is shipped. Since the expected number of lots ordered is 2.3 and each lot is 5 lbs, the expended number of pounds left over for one customer is 100 – (2.3)(5) = 88.5 lbs 5.30 (p.221). Suppose that the reaction time (sec) to a certain stimulus is a continuous 5....
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This note was uploaded on 03/26/2012 for the course STAT 350 taught by Professor Staff during the Spring '08 term at Purdue.
 Spring '08
 Staff
 Statistics

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