If a difference seen in sample results is "statistically significant" it means that

a.there is an important difference in the sample results.

b.there is an important difference in the population.

c.the difference observed in the sample was unlikely to have occurred if there is no difference in the population.

d.there is an important difference in the population that wasn't reflected in the sample results.

If the sample size for a poll increases from 100 people to 400 people, the margin of error

a.increases by a factor of 2, i.e. is multiplied by 2.

b.increases by a factor of 4, i.e. is multiplied by 4.

c.decreases by a factor of, i.e. is multiplied by.

d.decreases by a factor of, i.e. is multiplied by.

Student grade point averages (GPAs) are calculated by assigning a number to each letter grade earned, with A = 4, B = 3, C = 2, D = 1 and F = 0, then finding the average. A student proposes using the median of the numbers instead and calls this medGPA. A student has taken five courses (all an equal number of credit hours) and the grades were A, A, F, B, A. The usual GPA for these grades is 3.0. Should the student prefer using the median (medGPA)?

a.No, because medGPA is F = 0 for this student.

b.It doesn't matter, because medGPA is also B = 3.0 for this student.

c.No, because if the student takes one more course and gets an A or B, the usual GPA will go up but the medGPA will stay the same.

d.Yes, because medGPA is A = 4.0 for this student.