The Weight of a Product Is Measured in Pounds $\bar { X }$

Multiple Choice

The weight of a product is measured in pounds.A sample of 50 units is taken from a batch.The sample yielded $\bar { X }$
= 75 lbs. ,and we know that ?² = 100 lbs.Calculate a 95 percent confidence interval for ?.

A) $[ 71.25$$\quad$$\quad$$78.75 ]$
B) $[ 72.23$$\quad$$\quad$ 77.77]
C) $\left[ \begin{array} { l l } 47.28 & 102.72\end{array} \right]$
D) $\left[ \begin{array} { l l } 72.67 & 77.33\end{array} \right]$