How to find bandwidth of a composite signal that can be decomposed into five sine waves with given frequencies and having all peak amplitudes same ?
The bandwidth in this case would be the maximum frequency of the five sine waves. There is no problem if you know the five frequencies a priori. However, if that information is not available, you can do a DFT to find out the frequency content and find the index upto which the frequency content is non zero. That would give you your bandwidth.