Multiple Sclerosis (MS) Is an Autoimmune Disease That Affects the Brain

Multiple sclerosis (MS) is an autoimmune disease that affects the brain and spinal cord.
MS affects women more than men, and is most commonly diagnosed between the ages of
20 and 40. MS sufferers typically have problems of coordination and walking. The
standard care for some sufferers is a plastic device affixed to the lower leg and ankle. In
a recent test of this device, volunteers with MS were randomly assigned to two
experimental groups. The volunteers in one group used the plastic device; the volunteers
in the other group did not use the plastic device. Each individual was timed as he or she
climbed a set of stairs. Times, measured without the device (ND) and with the device
(D), are presented below. $$\begin{array} { | c | c | c | c | c | c | c | c | c | c | c | c | c | c | } \hline \begin{array} { c } \text { Stairs } \\\text { ND }\end{array} & 9.3 & 8.4 & 8.6 & 6.9 & 17.7 & 12.4 & 18.6 & 14.2 & 7.9 & 6.9 & 8.4 & 9.4 & 12.7 \\\hline \begin{array} { c } \text { Stairs } \\\text { D }\end{array} & 7.9 & 8.2 & 9.0 & 7.2 & 15.3 & 13.5 & 16.6 & 15.7 & 7.7 & 7.5 & 8.4 & 9.5 & 12.7 \\\hline\end{array}$$
-Calculate the values of these numerical summaries for the stair-climbing task without
the device: a) The mean __________
b) The standard deviation __________
c) The median___________
d) The interquartile range ______________ Note: The table above is reproduced below so that you need not flip back and forth. $$\begin{array} { | c | c | c | c | c | c | c | c | c | c | c | c | c | c | } \hline \begin{array} { c } \text { Stairs } \\\text { ND }\end{array} & 9.3 & 8.4 & 8.6 & 6.9 & 17.7 & 12.4 & 18.6 & 14.2 & 7.9 & 6.9 & 8.4 & 9.4 & 12.7 \\\hline \begin{array} { c } \text { Stairs } \\\text { D }\end{array} & 7.9 & 8.2 & 9.0 & 7.2 & 15.3 & 13.5 & 16.6 & 15.7 & 7.7 & 7.5 & 8.4 & 9.5 & 12.7 \\\hline\end{array}$$