The question consists of two statements numbered “I” and “II” given below it. You have to decide whether the data provided in the statements are sufficient to answer the question or not and choose the correct option accordingly. The ratio of time taken by pipe 'A' and pipe 'B' to fill the same tank is in the ratio of 3 : 4 respectively. pipe 'A' takes t hours to fill the tank and pipe 'C' takes (t + 4) hours to completely empty the same tank. If all the three pipes are opened together at 10 am then the tank gets filled at 5pm. For how many hours pipe C was opened during the process if it is known that pipe 'C' was closed in between the given duration of time.

(I) pipe 'A' and pipe C together can fill (7/10)th of the tank in 28 hours.

(II) pipe 'A' and pipe 'B' together can fill (7/8)th of the tank in 3 hours.