Answer:
18
Step-by-step explanation:
15 x 2 = 30
30 - 12 = 18
18 girls are in his class
#4 is 47, 48, 49
47+48+49=144
Step-by-step explanation:
Tammy's sample may not be considered valid because, on the first hand, it is said that she only asked students from her " Math Class".
If she wants to have a survey to find out the favorite subject of the students at her school, she must conduct a survey involving all the students in her school, not just in her class. What she did is just subjective. She should use a tally listing the different subjects and compare the number of students per subject. This way, she can have an objective representation of the least liked subjects and the most liked subjects of the students on her school.
Illustrating her survey through statistics may be more reliable and valid because it shows frequencies in which she can calculate easily and accurately the percentage of the number of students per subject, in a more objective manner.
This is because when we do verification of an
identity, we must work separately on both sides, and to see in the end
if we can get an equality. Because if we square both sides, that already means
that we assume that the equality exist in the beginning, so no need to
verify the identity.
