Chebyshev's Theorem states that at least 3/4 of the data lie within two standard deviations of the mean; therefore, in our case, the answer to part 3 is k=2.
4) Calculating the interval within two standard deviations of the mean,
[tex]\begin{gathered} \bar{x}\pm2s \\ \Rightarrow\bar{x}+2s=120+2*15=150 \\ and \\ \bar{x}-2s=120-2*15=90 \end{gathered}[/tex]
Thus, the answer to part 4) is 90 and 150
