3. TAILS OF THE CHI-SQUARE DISTRIBUTION
Let χ2k denote a random variable with central chi-square distribution with k degrees of freedom. For various applications explicit lower and upper bounds for tails of χ2k are important. Some estimates are well known. In Lemma 1 of Inglot and Ledwina [4], the following version of such an estimate was proved:
121u
(3.1) 2Ek(u)