Answer
$116\mathrm{W}, \quad 0.16\mathrm{h}\mathrm{p}$
Work Step by Step
$P=\displaystyle \frac{\Delta E}{\Delta t},\qquad 1 \mathrm{c}\mathrm{a}\mathrm{l} =4.186 \mathrm{J}$
Conversions to SI:
$\displaystyle \Delta E=\frac{2.5\mathrm{k}\mathrm{c}\mathrm{a}1}{1}\times\frac{4186\mathrm{J}}{1\mathrm{k}\mathrm{c}\mathrm{a}1},\qquad \Delta t=\frac{15\min}{1}\times\frac{60\mathrm{s}}{1\mathrm{m}\mathrm{i}\mathrm{n}}$
$P=\displaystyle \frac{\frac{2.5\mathrm{k}\mathrm{c}\mathrm{a}1}{1}\times\frac{4186\mathrm{J}}{1\mathrm{k}\mathrm{c}\mathrm{a}1}}{\frac{15\min}{1}\times\frac{60\mathrm{s}}{1\mathrm{m}\mathrm{i}\mathrm{n}}}=116\mathrm{W}$
Converting to horsepower,
$\displaystyle \mathrm{P}=\frac{116\mathrm{W}}{1}\times\frac{1\mathrm{h}\mathrm{p}}{746\mathrm{W}}=0.16\mathrm{h}\mathrm{p}$
