The vertex of a parabola that opens downward is at (0, 4). the vertex of a second parabola is at (0, –4). if the parabolas intersect at two points, which statement must be true? a. the second parabola opens downward. b. the second parabola opens upward. c. the points of intersection are on the x-axis. d. the points of intersection are of equal distance from the y-axis.

Ur environment is very sensitive to the amount of ozone in the upper atmosphere. the level of ozone normally found is 4.04.0 parts/million (ppm). a researcher believes that the current ozone level is not at a normal level. the mean of 2525 samples is 4.44.4 ppm with a standard deviation of 0.80.8. assume the population is normally distributed. a level of significance of 0.020.02 will be used. make the decision to reject or fail to reject the null hypothesis. answer tables