A researcher wants to know if the average test score at school X is higher than at school Y. For $60$ students at school X, the mean score is $78$, with a population standard deviation of $10$. For $55$ students at school Y, the mean is $74$, with a population standard deviation of $12$. What is the standardized test statistic?

• A. $1.45$
• B. $3.21$
• C. $2.83$
• D. $1.93$

Answer: (D)