2. A sample from an assumed normal distribution produced the values 9, 14, 10, 12, 7, 13, 12. a) What is the single best estimate of ! ? b) Find an 80% C.I. for !* ? 3. Based on the following data answer the questions n=10, > XY =4174, Ex =139, _Y =280, > x =1985 a/ what is the linear regression equation of y on x. b/ suppose the value of x=20, what will be the value of y. 4. According to the norms established for a reading comprehension test, students should average 84. If 45 randomly selected students averaged 87.8 with as.d of 8.6, test the null hypothesis 4** 1 against the alternative 17% , at 2 x . F ( x) . 5. In a survey of drug users in a large city, it is found that 18 out of 423 of them were HIV positive. Can we conclude that at 0=0.05 level of significance fewer than 5 percent of the drug users in the population are HIV positive? 6. In a study of aviophobia, a psychologist claims that 30% of all women are afraid of flying. If, in a random sample, 41 of 150 women are afraid of flying, test the null hypothesis p = 0.30 against En(x, ) P(x, ) at 2 x. F(x)