Each of 174 newly manufactured items is examined and the number of scratches per item is recorded (the items are supposed to be free of scratches), yielding the following data: Number of scratches per item 0 1 2 3 4 5 6 7 Observed frequency 16 35 43 33 19 15 9 4 Let X = the number of scratches on a randomly chosen item, and assume that X has a Poisson distribution with parameter u. (a) Find an unbiased estimator of u and compute the estimate for the data. [Hint: E(X) = u for X Poisson, so E(X) = ?] (Round your answer to two decimal places.) 2.60 (b) What is the standard deviation (standard error) of your estimator? Compute the estimated standard error. [Hint: x = u for X Poisson.] (Round your answer to three decimal places.) 1.735 X