The answer is 3...........
Answer:
b. The student's scores on the posttest would have a smaller standard deviation.
Step-by-step explanation:
The first test is taken before the material is covered in class so we expect the standard deviation to be high because not everyone's scores would be lying close to the mean. Equal number of students mastered most, some or almost none of the material from reading the textbook based on the pretest result. this means the data is varying, so the standard deviation is large.
Whereas, after the teacher has taught the material and given the homework, they must have understood most of the material. The test they take after teaching as a post test. The results of the post test would have a smaller standard deviation as most of the students would have scored good. Hence, the student's scores on the posttest would have a smaller standard deviation.
The given equations satisfy the given conditions. There are
2 equations and 2 unknowns, so a certain solution can be found.
This can be solved using substitution,
Substituting eqn 2 to eqn 1:
2(2y – 10) + 3y =1240
Simplifying,
y = 180
x = 350
