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Unformatted text preview: Stat 104, Section 4 Handout Solutions Benny, Thursday, 4:00pm, SC 309 Key concepts Random Variables (discrete vs. cont., expectations, means, variances, etc.) Join and conditional probability distributions (for discrete Random Variables) Binomial random variables Poisson Random Variables Practice Problems 1. Harvard College is composed of 52% women. There are 275 students in Stat 104, of which 115 are women. All of the following can be done using a computer tool such as Mathematica or the URL below. http://dostat.stat.sc.edu/prototype/calculators/index.php3?dist=Binomial a. Say there are 21 students in this section, and 14 of them are women. What is the probability of selecting 14 women from 21 students from Harvard? P ( X = 14) = 21 14 . 52 14 (1- . 52) 21- 14 = . 0722 b. What is the expected number of women from a simple random sample of 275 Harvard students? What is the standard deviation? x = np = 275(0 . 52) = 143 x = p np (1- p ) = p 275(0 . 52)(0 . 28) = 8 . 285 c. What is the probability of selecting exactly 115 women in a sample of 275 students from...
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