Nectar foraging by bumblebees suppose that, instead of the specific nectar function in example 2, we have an arbitrary function n with ns0d − 0, nstd > 0, n9std . 0, n0std , 0, and arbitrary travel time t.

(a) interpret the conditions on the function n.
(b) show that the optimal foraging time t satisfies the equation n9std − nstd t 1 t
(c) show that, for any foraging time t satisfying the equation in part (b), the second derivative condition for a maximum value