A sequence of biased coins is flipped; the chance that the rth coin shows a head is Or, where Or is a random variable taking values in (0, 1). Let Xn be the number of heads after n flips. Does Xn obey the central limit theorem when: (a) the Or are independent and identically distributed? (b) Or = 0 for all r, where O is a random variable taking values in (0, 1)