Raj is younger than I. Raj is younger than I am. Both are correct and should be accepted. "Raj is younger than me" is informal, and is said by almost everyone, BUT it is not acceptable in university examinations of English Grammar.
What are the "university examinations of English Grammar" of which you speak? Are you talking about examinations in a particular country? Are you talking about standardized examinations or examinations in individual grammar classes? If I wanted to make such a sweeping statement, I think I would need to do a great deal of research.
No, we make all comparisons in English (at least my dialect) using "than." You could say "Raj looks younger to me [than Peter does]," but I do not think that is what you are asking.
Ohhh ! But In Indian English (my dialect), since the comparison was made between Raj and me. Thus I thought of 'Raj is younger to me' as being the right. Ohh Now I see in the web, the accepted translation is 'Raj is younger than I (am) ' and this sentence is valid and a grammatically correct sentence. Thanks for clarifying mine's. :)
I love the exposure these Duolingo programs give me to the various dialects of English, especially where many of the native speakers of the target language also speak English natively (or nearly so), such as Irish, Welsh, Hebrew and now Hindi. As for "Raj is younger than I," it is not currently accepted, only "than me," but I have suggested it.
Yes, I've heard this construction regularly in Indian English. In other dialects, as James says, it has another meaning: 'It seems to me that Raj is younger'.
Now "Raj is younger than I" is not accepted. That is a sad development, and I don't understand why the change was made unless it's a result of all these comments. Even though a lot of people say "me," it is still not proper standard written English, so it should not be encouraged in a course like this. There is after all a distinction: "She likes her cat more than I" = She has more affection for her cat than I do; "She likes her cat more than me" = She prefers her cat to me.