The movement of a projectile, thrown upwards vertically, is described by the equation y = - 40x + 200x . Where y is the height, in meters, reached by the projectile x seconds after launch. Therefore, determine the instant when the projectile hits the ground.

According to a study conducted in 2015, 18% of shoppers said that they prefer to buy generic instead of name-brand products. suppose that in a recent sample of 1500 shoppers, 315 stated that they prefer to buy generic instead of name-brand products. at a 5% significance level, can you conclude that the proportion of all shoppers who currently prefer to buy generic instead of name-brand products is higher than .18? use both the p-value and the critical-value approaches.