During the depression, the rate of interest reduction, the expansion of money supply, stimulate economic development. During the expansion period, the interest rate increases, the money supply is reduced, and the economic development is suppressed. So, interest rates have a big impact on our lives. The research analysed five years’ trading connection between 1000 UK individuals split evenly into three age-based groups: 18-30, 30-50 and 50+, while using highest age being over 80. The five years ended in October 09 and so covered bull and bear markets, the banking collapse of 2008 and the volatile 2008/9 markets. In fact, currently not all monetary fund yields fell below 4%, there is also a part of the monetary fund yield is over 4%, according to the fund, according to data from the network every day until December 15, the top monetary fund, yield 5% or more. Gasoline is the largest oil product consumed in the United States last year, according to the U.S. energy information administration (EIA). Last year, gasoline consumption averaged about 9.3 million barrels a day (391 million gallons) a day, a record high, about 47 percent of U.S. oil consumption. Keynes argued that savings and investment were two interdependent variables, not two independent variables.