Let the required number of working hours per day be x.
More pumps, Less working hours per day (Indirect Proportion)
Less days, More working hours per day (Indirect Proportion)
Pumps | 4 | : | 3 | ![]() | :: 8 : x |
Days | 1 | : | 2 |
4 x 1 x x = 3 x 2 x 8
![]() | (3 x 2 x 8) |
(4) |
x = 12.
Sum of digits = (5 + 1 + 7 + x + 3 + 2 + 4) = (22 + x), which must be divisible by 3.
x = 2.