"The majority of the people think that I am crazy."
Translation:La mayoría de la gente cree que estoy loco.
the mental process indicated by pensar is more of trying-to-solve-a-problem type, like when Newton was thinking why apples fall and we struggling how the sentence should be translated
meanwhile, the sentence structure when you think something about someone in English, in my understanding, is you BELIEVE that person is the kind of person you think s/he is, so it should be cree
This is confusing. I thought "cree" was "to believe", and even the dictionary hints suggest so. While "...believe that I'm crazy" is very similar to "...think that I'm crazy", it's not quite the same, and it seems odd that I was marked wrong for "La mayoria de la gente piensan que estoy loco" (unless I've made a silly mistake somewhere)
Hmmm OK, thank you. I had a look at the dictionary and found "pensar", when used as a transitive verb, given with an exmaple of "to think something of somebody" . As far as I can see, that should apply here, but please correct me if I'm missing something. I'm also still confused about "pensar" being singular. Isn't "The majority of the people" equivalent to "they", so it's "they think...", hence "piensan"?
"The majority of the people" is not equivalent to they - in English (and, apparently, in Spanish), "the majority" is treated as the subject, while "of the people" could be discarded without affecting the structure of the sentence. And, as rspreng said, "La mayoria" is singular.
In English, this would be "The majority of the people thinks that I am crazy" - here "thinks" sounds weird, but only because it's next to "people". "Of the people, the majority thinks that I am crazy" is more clearly correct.
It turns out that whether you treat la mayoría de la gente as singular or plural depends on whether you're stressing the mayoría part or the gente part. In this particular case, both are singular and, therefore, the entire phrase should be treated as singular.
In other similar expressions, however, it is not so clear cut. For example, if you said la mayoría de las personas there is a logical quandary about which part of the phrase determines the number of the entire expression. Spanish speakers are not consistent in their treatment of this. So, it's best not to rely too heavily on simple rules like la mayoría is singular and that makes the phrase singular.
Elsewhere on Duo, for example, you will see la mayoría de las personas treated as plural. Here's some more info for anyone still curious about this topic.