What new developments starting in the 1980s have changed macroeconomic thought?

mark, a civil engineer, entered into a contract with david. as per the contract, mark agreed to design and build a house for david for a specified fee. mark provided david with an estimation of the total cost and the contract was mutually agreed upon. however, during construction, when mark increased the price due to a miscalculation on his part, david refused to pay the amount. this scenario is an example of a mistake.

Salt corporation's contribution margin ratio is 78% and its fixed monthly expenses are $30,000. assume that the company's sales for may are expected to be $89,000. required: estimate the company's net operating income for may, assuming that the fixed monthly expenses do not change.

Lambert manufacturing has $100,000 to invest in either project a or project b. the following data are available on these projects (ignore income taxes.): project a project b cost of equipment needed now $100,000 $60,000 working capital investment needed now - $40,000 annual cash operating inflows $40,000 $35,000 salvage value of equipment in 6 years $10,000 - both projects will have a useful life of 6 years and the total cost approach to net present value analysis. at the end of 6 years, the working capital investment will be released for use elsewhere. lambert's required rate of return is 14%. the net present value of project b is: