Depleting Capital

A man has a capital of £20000 for which he receives interest at 5 per cent.; if he spends £1800 every year, show that he will be ruined before the end of the 17th year; having given $\log 2=.3010300$, $\log 3=.4771213$, $\log 7=.8450980$.

H. S. Hall & S. R. Knight, Higher Algebra (1891) · Ch. XVIII. Interest and Annuities, Examples XVIII.b, No. 12