[QUOTE=Tayyab Imdad Seastani;1096960]Q6 ??[/QUOTE]

Q#6(a)

5 x 7 x 12 = 420

So after 415 seconds

From the preliminary first 5, 7 and 12 ticking seconds together.

Q#6 (b)

One pipe filling the pool in 5 hours = 1.25 times

If the second pipe is used with the same intensity of pressure for filling then in the given fives hours filling cspacity gets double

So two pipes filling a pool with the same pressure in 5 hours =

2 x 1.25 (times) = 2.50 times

Here the two pipes with the same capacity of filling the pool divided by 5 hours

5 hours /2.50 = 2 hours for the pipes with 1.25 times

Slower pipe will take 5 hours for 1 time filling the pool as hour with slower capacity.

Right I think ?? maths is difficult.

[QUOTE=soft rock;1107413]Q#6(a)

5 x 7 x 12 = 420

So after 415 seconds

From the preliminary first 5, 7 and 12 ticking seconds together.[/QUOTE]
The LCM of 5,7,12 is 420 seconds. The starting point (at 12 am) is where the time-end of the 5 second period, the time-end of the 7 second period, and the time-end of the 12 second period overlap (or equal); therefore, how can you disregard 5 seconds from 420 and make the answer 415?

Could you please explain your rationale?