Final answer:
Without specific waiting time data, the expected value of the difference between morning and evening waiting times cannot be calculated. It is the difference between their individual expected values, and the variance would be the sum of their individual variances, assuming independence.
Step-by-step explanation:
To address the question about the expected value and variance of the difference between morning and evening waiting times on a given day, we would need more information about the waiting times themselves. Since this information has not been provided, we cannot provide a numerical answer. However, we can discuss the relation between expected values and variances when considering differences.
The expected value (or mean) of the difference between two variables is the difference between their expected values. If the expected waiting times in the morning and evening are E(M) and E(E) respectively, then the expected value of the difference would be E(M) - E(E).
The variance of the difference between two independent variables is the sum of their variances. Assuming that morning and evening waiting times are independent, if Var(M) is the variance of morning waiting times and Var(E) is the variance for evening, the variance of the difference would be Var(M) + Var(E).