# Past Exam for STAT 100 - ELEM STAT & PROB at Maryland (UMD)

## Exam Information

 Material Type: Exam 2 Professor: Staff Class: STAT 100 - ELEM STAT & PROB Subject: Statistics and Probability University: University of Maryland Term: Spring 2003 Keywords: CombinationsDistributionCalculatorsStandard DeviationExpected ValuesIndependenceApproximationProbabilitiesProbability SampleExpectation  ## Sample Document Text

Stat 100 Exam 2 B Spring 2003 Calculators allowed. All work mllst be shown 10 receive full credit. 1. Let the random variable X denote the number of tails minus the number of heads in 3 tosses ofa coin. a) (10 pts) Determine the probability distribution of X. b) (10 pts) Determine the expectation, variance, and standard deviation of X. 2. 80% of all freshman at a certain university live on campus. 11 freshmen are selected at random. a) (5 pts) What is the probability that at least 8 live on campus? b) (5 pts) What is the probability that 5 do not live on campus? c) (5 pts) Of those selected, what is the probability that more than 5 and fewer than 10 live on campus? d) (5 pts) Calculate the mean and standard deviation of X = number that live on campus. 3. The diameters of Douglas firs grown at a Christmas tree farm are normally distributed with a mean of 4.5 inches and a standard deviation of].5 inches. a) (10 pts) What is the probability that a randomly selected tree has a di...

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