given datas

\(\displaystyle\mu={335}\)

\(\displaystyle\sigma={50}\) X=284 now we have to find Z score

so from the formula the Z score corresponding to observation X=284 is we have \(\displaystyle{Z}={\frac{{{X}-\mu}}{{\sigma}}}={\frac{{{284}-{335}}}{{{50}}}}=-{1.02}\)

\(\displaystyle\mu={335}\)

\(\displaystyle\sigma={50}\) X=284 now we have to find Z score

so from the formula the Z score corresponding to observation X=284 is we have \(\displaystyle{Z}={\frac{{{X}-\mu}}{{\sigma}}}={\frac{{{284}-{335}}}{{{50}}}}=-{1.02}\)