Despite the booming business activity of the 1920s, the economy showed some weaknesses. one of these weaknesses was
the increase of taxation and government spending
in the agricultural sector
the excessive restriction on borrowing by the federal reserve
a decline of consumer demand

One of these weaknesses during this time was "in the agricultural sector," since during this time consumer demand of many farm goods dropped, which brought down prices. 

The have over 100 billion people in america

the imf provides economic advice and loans to developing countries.

economic advice:

policy advice to governments and central banks based on analysis of economic trends and cross-country experiences; research, statistics, forecasts, and analysis based on tracking of global, regional, and individual economies and markets; technical assistance and training to countries improve the management of their economies.

loans:

loans to countries overcome economic difficulties; concessional loans to fight poverty.

these are the goals the fund wants to achive.