Answer
$3.0\times 10^4$ repetitions
Work Step by Step
First of all, we find the work done
$W=F\Delta y$
$\implies W=(12lb)(1.3ft)=15.6ft-lb$
Now, we convert the work done into calories as
$W=(15.6ft-lb)(\frac{1m}{3.281ft})(\frac{4.448N}{lb})(\frac{1cal}{4186N.m})=5.05\times 10^{-3}cal$
Now we can find the required repetitions as
$repetitions=\frac{150}{5.05\times 10^{-3}Cal}=3.0\times 10^4$
