The Wechsler Intelligence Scale for Children is approximately normally distributed, with mean 100 and standard deviation 15.
(a) What is the probability that a randomly selected test taker will score above 125?
(b) What is the probability that a randomly selected test taker will score below 90?
(c) What proportion of test takers will score between 110 and 140?
(d) If a child is randomly selected, what is the probability that she scores above 150?
(e) What intelligence score will place a child in the 98th percentile?
(f ) If normal intelligence is deﬁned as scoring in the middle 95% of all test takers, ﬁgure out the scores that differentiate normal intelligence from abnormal intelligence.