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Question # 3. In a certain school with 100 senior students. 24 students study Data Structure. 55 study Mathematics and 20 study neither subject. A senior student was selected at random, nd the probability that the student: A. studies at least one of these subjects; B. studies both subjects: C. doesn't study both subjects; D. Studies exactly one of these subjects; E. Studies Mathematics but not Data Structure. Question # 4. Measurements of scientific systems are always subject to variation, some more than the others. There are many structures for measurement error, and statisticians spend a great deal of time modeling these error. Suppose the measurement error X of a certain physical quantity is decided by the density function. A. Determine K that render f(x) a valid density function. B. Find the probability that arandom error in measurement is less than 1/2. f(x)={k(3x'), 49:1 0, elsewhere