SC Adj+Adj+noun vs Adv+Adj+noun

[padma.gmat]

In chapter 6 of manhattan SC guide author explained about Adj+Adj+noun format and Adv+Adj+noun with examples

Wrong:James Joyce is Max's SUPPOSEDLY Irish ancestor.
Right:James Joyce is Max's SUPPOSED Irish ancestor.
and
Wrong:Max's grandmother is his SUPPOSED Irish ancestor.
Right:Max's grandmother is his SUPPOSEDLY Irish ancestor.

Can some one explain clearly when 2 use the adverb and when to use the adjective?

thank u

[RonPurewal]

In chapter 6 of manhattan SC guide author explained about Adj+Adj+noun format and Adv+Adj+noun with examples

Wrong:James Joyce is Max's SUPPOSEDLY Irish ancestor.
Right:James Joyce is Max's SUPPOSED Irish ancestor.
and
Wrong:Max's grandmother is his SUPPOSED Irish ancestor.
Right:Max's grandmother is his SUPPOSEDLY Irish ancestor.

Can some one explain clearly when 2 use the adverb and when to use the adjective?

thank u

it's a meaning issue -- "supposed(ly)" has to modify whatever is actually in doubt.

in the first group of sentences, the issue is whether james joyce is actually max's ancestor at all. (james joyce was definitely irish; that's not an issue.) therefore, you want "supposed ... ancestor".

in the second group of sentences, the issue is whether max's grandmother is irish. (she is his grandmother, so she is clearly his ancestor.) therefore, you want "supposedly irish".

[hemant.rao110]

ron purewal,

is this grammatically correct or there is a pronoun issue ...
i.e. his don't have an antecedent

[jnelson0612]

ron purewal,

is this grammatically correct or there is a pronoun issue ...
i.e. his don't have an antecedent

I think you are making an excellent point! Yes, Max does not exist in this sentence as a noun, so Max cannot be the antecedent for "his".