- AThe repairs were carried out by a contractor rather than by the water office's own staff
- BWater lost in that zone had already been falling by about nine per cent a year for each of the four years before the repairs, as the oldest pipes were steadily taken out of use under a replacement programme that ran on unchanged through last year
- CA few of the joints repaired last year had been repaired once before, several years earlier
- DThe zone has more taps in it than any other zone the office supplies
Step-by-Step Solution
The zone was already shedding nine per cent of its losses every year without any joint repairs, and the programme that produced that fall carried on regardless. The whole of last year's nine per cent is therefore accounted for before the repairs are even brought in, and the office has nothing left over to credit them with. Who did the work, whether some joints had been repaired before and the number of taps in the zone all leave the size of the saving exactly where it was.
Answer: B) Water lost in that zone had already been falling by about nine per cent a year for each of the four years before the repairs, as the oldest pipes were steadily taken out of use under a replacement programme that ran on unchanged through last year