Chapter 8.4, Problem 70E

To determine

The correct statements out of the following statements:

(A): Both the mean and standard deviation show an upward trend from $2000$ on.

(B): The mean but not the standard deviation, shows an upward trend from $2000$ on.

(C): The demand for electric power peaked in the second half of $2001$.

(D): The standard deviation was larger in the second half of $2002$ that in the second half of $1999$.

(E): The mean of the monthly means in $2000$ was lower than that for $2002$, but the standard deviation of the monthly means was higher.

If the chart shows the approximate monthly means of the power grid frequency, in $\frac{1}{1000}$ cycles per second, and $0.0$ is the desired frequency of exact $60$ cycles per second.