Is the sentence structure right?

Cool Breeze

In informal style grammatical considerations are often cast aside in all languages, and using because without a main clause is very common:

"Why didn't you call him?"

"Because I didn't know his number."

 Since and as would be just as "grammatical" as because in the above sentence but they just aren't used.

^{I don’t think the correct answer should be dependent on  the number of student based on the original question which was}

^{only 5% of the students are placed after completion of their training. Clearly, the subject is the percentage which is “5%”, not the student; if my understanding is true.}

^{My question was, should “is” be used instead of “are”? And I think it should.}

^{If this statement is transformed into a question, it would be “what is the percentage of}

^{Job placement after the students completed their training?  Not how many students are placed.}

^{For the same reason:}

^{A set of tires for my new car costs me $500, not “cost”.}

^{A group of students was found lost in the forest.}

^{Common belief is plural verb should be used in this kind of sentence construction.}

^{We need the gurus to clear up this one….}

Hi Goodman

^{A group of students was found lost in the forest. (If the students are perceived as a group, is should be used.)}

^{Hi Liat,
I think what you said is contradicting.  You are saying both of my exmaples are grammatically acceptable only with the right perception.}

 A group of students was found lost in the forest. (If the students are perceived as a group, is should be used.) 
If the rule sticks as you described about
50% of the students.. then my first example could not be accpetable because the pertinent word is "students" like you said.