Question 1 is no doubt B, because Johnny only asked the students in his science class, not the entire school's population. As for question 2, If you could give me a picture of the actual graph, that would be fantastic. Until then, i don't think I can answer Q2 properly.
It's not clear that the science class is a good sample of the school as a whole. It may be an elective or for a particular grade, making it a biased sample.
For Question 2 I'll try to create the histogram from your description.
N TOP BOTTOM
9 3 3
10 5 4
11 2 3
If that's accurate the BOTTOM, B, group has longer arms, due to a single person measuring 11 instead of 10.
Neither B or D is really a good answer making me think I transcribed the table incorrectly. I'd guess D
