These are bounds on the probability of a random variable $X$ occurring within an interval.
A non-negative random variable $X$ takes on large values (relative to its mean) with low probability.
$$ P(X \geq a ) \leq \frac{\mathbb{E}[X]}{a} $$
A random variable $X$ deviates from its mean with quadratic drop-off in probability.
$$ P(|X- \mu| \geq c) \leq \frac{\sigma ^2}{c^2} \text{ where } \mathbb{E}[X]=\mu, \text{var}(X) = \sigma^2 $$
$$ P(|X-\mu| \geq k\sigma) \leq \frac{1}{k^2} $$