A contractor needs to buy nails to build a house. The nails come in small boxes and large boxes. Each small box has 200 nails and each large box has 400 nails. The contractor bought twice as many small boxes as large boxes, which altogether had 3200 nails. Graphically solve a system of equations in order to determine the number of small boxes purchased, x, x, and the number of large boxes purchased, yy.

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.