#### Problem 19E

19. A man starts walking north at $4 \mathrm{ft} / \mathrm{s}$ from a point $P$. Five minutes later a woman starts walking south at $5 \mathrm{ft} / \mathrm{s}$ from a point $500 \mathrm{ft}$ due east of $P .$ At what rate are the people moving apart 15 min after the woman starts walking?