Impromptu is an unrehearsed speech. Not rehearsing would not allow speakers to gather 100% of their thoughts.
Question 1) Complete sentence
Question 2) Sentence fragment
Question 3) Run-on sentence
Question 4) Inverted
Question 7) Comma fault (?)
Question 8) Compound
Question 9) Compound-complex
Question 10) Easily, so
Question 11) Fruit; it
Question 12) Film;
Probability that the 7th grader is a boy = number of boys/(total kids) = 4/(4+4) = 1/2
Probability that the 8th grader is a boy = 5/(5+7) = 5/12
Probability that both are boys = 1/2*(5/12) = 5/24 or 20.8%
I hope this helps!