MATH 115 Midterm: MATH 115 UPenn m115 sExam 2
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720: what are the expected value and the variance 2 of a random variable x dis- tributed on the interval [0, 2] with the probability density function f (x) = x/2 for. What is the expected number of pairs of socks that come back? (hint: this is the sum of the expectations of the number, 0 or 1, of each individual pair that come back. ) (a) 22: a student knows how to do 15 out of the 20 core problems for a given chapter. If the ta chooses 3 of the core problems at random for a quiz, what is the probability that the student knows how to do exactly 2 of them? (a) 64: 6% of type a spark plugs are defective, 4% of type b spark plugs are defective, and 2% of type c spark plugs are defective.
