The claims of students look hollow when they attribute their poor performance to difficulty of examination.

infer : deduce or conclude (something) from evidence and reasoning rather than from explicit statements.
impute : represent (something, especially something undesirable) as being done or possessed by someone; attribute.
inhere : exist essentially or permanently in.
inundate : overwhelm (someone) with things or people to be dealt with.
attribute : regard something as being caused by.


Synonym of attribute is impute