Which of these would have the greatest potential energy?
a) a roller coaster at the top of a hill.
b) a roller coaster half-way up the hill.
c) a roller coaster half-way down the hill.
d) a roller coaster at the bottom of the hill.

The output voltage of a power supply is assumed to be normally distributed. sixteen observations are taken at random on voltage are as follows: 10.35, 9.30, 10.00, 9.96, 11.65, 12.00, 11.25, 9.58, 11.54, 9.95, 10.28, 8.37, 10.44, 9.25, 9.38, and 10.85