(a) There is a probability of 0.90 that a t random variable with 23 degrees of freedom lies between -x and x. Find the value of x.
(b) There is a probability of 0.975 that a t random variable with 60 degrees of freedom is larger than y. Find the value of y.
(c) What is the probability that a chi-square random variable with 29 degrees of freedom takes a value between 19.768 and 42.557?