could you give me some reasons for questions below?

context:
the surveys of more than 150,000 students show that some 15% of pupils in elementary and lower secondary high schools,roughly corresponding to ages 7 to 16,in Scandinavia are involved in bully/victim problems with some regularity--either as bullies,victims or both.Approximately 9% are victims,and 7% bully other students with some regularity.A relatively small proportion(15%-20%)of the victims are themselves bullies of other pupils.There figures probably underestimate the problem,and there are indications that the level of bullying has risen over the past 10-15 years. More worrying,it is the more frequent and severe forms of bullying that have increased most.

decide the following statement is true ,false,or the information is not given:

The problem is definitely more serious than what these surveys'figures have shown.
my answer is that the information is not given,but the correct answer in my book is "false".

another example:
There are several common assumptions about the causes of bullying for which there is no supportion evidence. They include claims that bullying is a consequence of large class or school sizes,or of the competition for grades and other pressures that school generates....

statement:Competition for grades and other pressures should take the responsibility of school bullying (correct answer is "not given")

comparing these two questions and their answers,I am totally confused.
if i followed the thinking way of question 1,i will give "false" to question 2.
vice versa.As a chinese . i know there are big differences between us.Thus,i
am eager to know how do you think of these two questions.Thank u!

[Tdol]

1 It says 'probably', which is not the same as 'definitely'. So it is false.
2 It is an assumption not a fact.