According to the StatsCanada "population clock", Canada's population was estimated at 34,501,798 people on July 1st, 2011, and is increasing by one person every 80 seconds.

If you want to specify a population figure that takes into account the range of numbers over the full year (that is, where the number of sig figs reflects the uncertainty of whether you're talking about January 1, 2011, or Dec 31, 2011),Canada's population in 2011 is approximately:

A) 30 million people.
B) 34.5 million people.
C) 35. million people.
D) 34.89 million people.

Question

According to the StatsCanada "population clock", Canada's population was estimated at 34,501,798 people on July 1st, 2011, and is increasing by one person every 80 seconds. 

If you want to specify a population figure that takes into account the range of numbers over the full year (that is, where the number of sig figs reflects the uncertainty of whether you're talking about January 1, 2011, or Dec 31, 2011),Canada's population in 2011 is approximately:

A) 30 million people.
B) 34.5 million people.
C) 35. million people.
D) 34.89 million people.

anonymous · Answer

The change in population over the year is 1/80s * 60 s/min * 60 min/hr * 24 hr/day * 365 days in 201 = 394, 200.  Hence the population should be written 34,501,798 +/-  197,100 to express exactly what's asked.

But if you write a restricted number of significant digits, you can rely on people assuming the last digit you write is good only to +/- 1.  So if you cut off your number at the 100,000s place, viz. 34.5 million, you can be sure people will assume the precision of that number is about +/- 100,000, which is about right.

poofypenguin · Answer

That seems very reasonable! Thank you very much! :D