Preface to the Third Edition This new edition has been enlarged to contain all the mate- rial in the second edition, an expanded chapter on statistics includes sample size estimations for means and portions, and a totally new chapter on financial math- ematics In adding this new chapter we have also included a number of tables that aid in performing the calculations on annuities, true interest, amortization schedules, compound interest, systematic withdrawals from interest accounts, etc. The treatment and style of this material reflect the rest of the book, i.e, clear explanations of concepts, relevant formulas, and worked examples. The new financial material includes analyses not readily found in other sources, such as the effect f lump sum payments on amortization schedules and a novel in-out formula"that calculates current regular deposits to avings in order to allow the start of systematic withdrawals of a specified amount at a later date. While many engineer mathematicians, and scientists have found much use for this handy pocket book, this new edition extends its usage to them and to the many business persons and individuals who make financial calculations PhiladelphiaPreface to the Third Edition This new edition has been enlarged to contain all the mate￾rial in the second edition, an expanded chapter on statistics that now includes sample size estimations for means and proportions, and a totally new chapter on financial math￾ematics. In adding this new chapter we have also included a number of tables that aid in performing the calculations on annuities, true interest, amortization schedules, compound interest, systematic withdrawals from interest accounts, etc. The treatment and style of this material reflect the rest of the book, i.e., clear explanations of concepts, relevant formulas, and worked examples. The new financial material includes analyses not readily found in other sources, such as the effect of lump sum payments on amortization schedules and a novel “in-out formula” that calculates current regular deposits to savings in order to allow the start of systematic withdrawals of a specified amount at a later date. While many engineers, mathematicians, and scientists have found much use for this handy pocket book, this new edition extends its usage to them and to the many business persons and individuals who make financial calculations. R. J. T. Philadelphia