Use the IS-LM model to predict the effects of each of the following on income, and interest rate. In each case, explain what action the central bank should take in order to keep income from at its initial level: a) after the intervention of a new high-speed computer chip, many firms decide to upgrade their computer systems. b) a wave of credit-card fraud increases the frequency with which people make transactions in cash. c) a best seller titled Retire rich convinces that the public to increase the percentage of their income devoted to saving. d) An increase in tax rates