Relationship of signal Frequency and the SNR?
I think this is a fairly trivial question, assuming that the input signal is not filtered by the low pass filter (input signal frequency is much lower than the low pass filter bandwidth.) The reason I'm inclined to hastily jump to such assumptions is due to the format of the question, which seems to inquire if the reader is aware that noise power is the integral of noise level over the noise bandwidth of the system. Also, I think everybody reading the question would agree that it would be plainly unsolvable if these assumptions are not made.

If the case is as above, the noise power will decrease by a factor of 4, while the signal level is kept constant, and the SNR will increase to 36.02 dB at the filter output.