In certain deep parts of oceans, the pressure of sea water, P
,
P
,
in pounds per square foot, at a depth of
d
d
feet below the surface, is given by the following equation:

P
=
14
+
8
d
9
P
=
14
+
8
d
9

If a scientific team uses special equipment to measures the pressure under water and finds it to be 310 pounds per square foot, at wh