18) A survey claims that 9 out of 10 doctors (Le, 90%) recommend brand 2 for their patients who have children. To test this claim against the alternative that the actual proportion of doctors who recommend brand Z is less than 90%. a random sample of doctors was taken. Suppose the test statistic is z = -1.95. Can we conclude that Ho should be rejected at the a) a=0.10. b) a: 0.05, and c) a = 0.01 level