Average Rate of Return The following data are accumulated by McDermott Motors Inc. evaluating two competing capital investment proposals: Testing Equipment Diagnostic Software $48,000 9 years $28,000 4 years ?.) $3,360 Amount of investment Useful life Estimated residual value Estimated total income over the useful life Determine the expected average rate of return for each proposal. If required, round to one decimal place. Testing Equipment Diagnostic Software $19,440