The following data occurs chronologically from left to right: $$\begin{array} { l l l l l l }
15.2 & 19.7 & 16.0 & 11.1 & 14.8 & 14.5
\end{array}$$ The number of runs up and down is:
A) 2.
B) 3.
C) 4.
D) 5.
E) none of these.

Question

The following data occurs chronologically from left to right: $$\begin{array} { l l l l l l } 
15.2 & 19.7 & 16.0 & 11.1 & 14.8 & 14.5
\end{array}$$ The number of runs up and down is:
A) 2.
B) 3.
C) 4.
D) 5.
E) none of these.

Quizplus · Accepted Answer

We have four runs down: 15.2-11.1, 19.7-16.0, 16.0-14.5, and 14.8-end. We also have four runs up: 11.1-14.8, 14.8-15.2, 15.2-16.0, and 16.0-19.7. This gives a total of four runs up and four runs down for a total of eight; however, we don't count the last data point because there is no next point to compare it to, so the answer is four runs up and four runs down for a total of eight minus one, or $\boxed{	extbf{(C) }4}$.

The Following Data Occurs Chronologically from Left to Right 15.219.716.011.114.814.5\begin{array} { l l l l l l } 15.2 & 19.7 & 16.0 & 11.1 & 14.8 & 14.5\end{array}15.2​19.7​16.0​11.1​14.8​14.5​

The Following Data Occurs Chronologically from Left to Right $\begin{array} { l l l l l l } 15.2 & 19.7 & 16.0 & 11.1 & 14.8 & 14.5\end{array}$