25 people can dig the hole of 50 m deep in hours
Explanation
4 people can dig a hole 20 m deep in 3 hours
So, 1 people can dig a hole 20 m deep in (3×4)hours= 12 hours [If the number of people decreases, then the time taken to dig the hole will increase]
and 1 people can dig a hole 1 m deep in ()hours = hours = 0.6 hours
Now, if 1 people dig the hole of 50 m , then the time needed = (0.6×50) hours = 30 hours
So, 25 people can dig the hole of 50 m deep in = hours