Answer
V = 8.09 x $10^{4}$ Imperial gal ( to three significant figures).
Work Step by Step
First we have to find the volume of tank than convert it to Imperial gallons.
V = $\frac{4}{3}\timesπ\times{r}^{3}$
V = $\frac{4}{3}\times3.14\times({175.0 in})^{3}$
V = 22,437,917 $in^{3}$
We can express this in Imperial gallons using conversion factor: $\frac{1 (imperial gal)}{277.4 (in^{3})}$
V = 22,437,917 $in^{3}$ x $\frac{1 (imperial gal)}{277.4 (in^{3})}$
V = 80,886 Imperial gal
V = 8.09 x $10^{4}$ Imperial gal ( to three significant figures)