STATISTICS HELP ASAP!!?

I have an exam coming up tomorrow and this question was on the study and I really don't understand how to do this




According to Chebyshev Rule, for any data set, P(|X-mean|< k sd) > 1-(1/k^2) that is the proportion of data within k standard deviations is at least 1-k^2.

1) what percentage of the data falls within three standard deviations of the mean