Final answer:
The term 'PW' refers to the present worth of future cash flows and 'expected PW' is an average of present worths based on probabilities of outcomes. More context is needed for the specific calculation of 'pw' and 'PA' as the provided information lacks clarity on financial or investment terms and the discount rate used.
Step-by-step explanation:
The question relates to the calculation of present worth (PW) for each estimated value and finding the expected PW. The present worth is used in engineering economics to determine the current value of a future cash flow when discounted at a particular interest rate. The use of subscripts such as 'W' for whites and 'A' for African Americans seems to relate to a statistical analysis concerning two different population proportions. However, without specific values or a context for 'pw' and 'PA', it's unclear what these proportions are or how they directly relate to a calculation of present worth. If 'pw' and 'PA' were related to future cash flows or benefits, their present worth would be calculated by discounting these future values back to the present using an appropriate discount rate. The expected PW would typically be an average or statistically expected value of several present worth calculations, based on probabilities of different outcomes.
To provide a precise answer, more context is needed regarding what 'pw' and 'PA' represent in terms of financial or investment terms and the rate at which future values are being discounted to the present.