Problem 4.4 According to a survey, 85 percent of the people wear mask every day to work. A sample of 240 citizens found that 65 had skipped wearing a mask that day. Using the .01 signicance level to check whether the citizens are more likely to skip wearing a mask, what is the decision rule? Problem 5.2 Jerry observes the difference on sales between group X and group Y. The 70 days sample show that group X sold 1700 smartphones in average per day. Meanwhile, the 80 days sample show group Y sold 1800 smartphones in average per day. The population standard deviation for group X is $270 and $320 for group Y. Using the 0.05 significance level, what is the null hypothesis and alternate hypothesis if Jerry conclude that the average sales of group Y is lower than group X's