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 2 against the alternative , at 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