Answer:
3 1/3 cents per hour
Explanation:
The 1845 earnings per hour were ...
(40 cents)/(12 hours) = (10/3) cents/hour = 3 1/3 cents/hour
__
Comment on the rate of increase
That's an average rate of increase of wages of about 3.28% per year, substantially higher than the 2.04% average rate of inflation over that period. The mill girls' wage is roughly equivalent to $0.78 per hour in 2001 dollars.