Answer
$\approx 15, 073,099.75 $ N-m (or Joules)
Work Step by Step
The work done is defined as follows:
$W=(\pi r^2 h)(\rho)(d)$
Here, the water is pumped to 4 m above the 5 m high reservoir.
Thus, we have
$W=\int_{-5}^0[\pi (25-y^2) dy] (9800) (4-y)$
or, $W=\int_{-5}^0[9800 \pi (25-y^2) (4-y) dy$
or, $W=\dfrac{14,393,750 (\pi) }{3} \approx 15, 073,099.75 $ N-m
