73. Indicate the number of significant figures in each of
the following:
a. This book has over 500 pages.
b. A mile is just over 5000 ft.
c. A liter is equivalent to 1.059 qt.
d. The population of the United States is more than
310 million.
e. A kilogram is 1000 g.
f. An airplane cruises at around 600 mi/h.