Equity theory, most popularly known as equity theory of motivation, was first developed by John Stacey Adams, a workplace and behavioral psychologist, in 1963.
On average there are about 4.3 weeks in a month. Each week is 7 days, and there are normally either 30 or 31 days in a month, so there are usually between 4.2 and 4.4 weeks per month. The exception is February because it has fewer days, so there are about 4 weeks in that month. On average there are about 4.3 weeks in a month.
They all have 4 weeks, but February is the only one to have exactly 4 weeks (except in Leap years when it has 4 weeks and 1 day). April, June September and November each have 30 days = 4 weeks and 2 days. The rest of the months each have 31 days = 4 weeks and 3 days.