Question

A certain geyser was determined to have eruptions with a Mean duration of 3.31 min and a standard deviation of 1.04 min. A sample of n=43 eruptions were recorded. Using Chebychev's Theorem, how many of the eruptions lasted between 1.23 min and 5.39 min.

there both 3 sd's away but i have no clue how to do this