The figure shows several different reflections of ab . which segment is the image of after a reflection across the y-axis?

If it's a reflection across the y-axis, then the figure would look as if it was seen in the mirror. without the image of the figure, i can't much but think of ab as your left hand, then the reflection across the y-axis would look like your right hand. hope that .

The dean of students mailed a survey to a total of 400 students. The sample included 100 students randomly selected from each of the freshman, sophomore, junior, and senior classes on campus last term. What sampling method was used?

Solution: The sampling method used here is stratified sampling. Because the sample included the students from each of the freshman, sophomore, junior and senior classes.

Stratified sampling is is a probability sampling method and a form of random sampling in which the population is divided into two or more groups (strata) according to one or more common attributes and and a sample is selected by some design within each group.