ν=343ms (the speed of sound at 20°C)
Three harmonics, all odd multiples of 25.
f9=225Hz, f11=275Hz, et cetera
For open pipes,
For half-open pipes (e.g. closed),
The key to this question is knowing that "closed" pipes must have harmonics in odd multiples, to ensure an antinode being at the open end and a node being at the closed end.
Hence, the pipe is closed, the fundamental frequency is f1=25Hz, and the pipe must be,