A Coffee House Owner Knows That Customers Pour Different Amounts $12.5 \pm 2.228 \left( \frac { 0.5 } { \sqrt { 9 } } \right)$

A coffee house owner knows that customers pour different amounts of coffee into their cups. She Samples cups from 10 costumers she believes to be representative of the customers and weighs the Cups, finding a mean of 12.5 ounces and standard deviation of 0.5 ounces. Assuming these cups of Coffee can be considered a random sample of all cups of coffee which of the following formulas Gives a 95% confidence interval for the mean weight of all cups of coffee?

A) $12.5 \pm 2.228 \left( \frac { 0.5 } { \sqrt { 9 } } \right)$
B) $12.5 \pm 2.262 \left( \frac { 0.5 } { \sqrt { 9 } } \right)$
C) $12.5 \pm 2.262 \left( \frac { 0.5 } { \sqrt { 10 } } \right)$
D) $12.5 \pm 2.228 \left( \frac { 0.5 } { \sqrt { 10 } } \right)$
E) $12.5 \pm 1.969 \left( \frac { 0.5 } { \sqrt { 10 } } \right)$