A mobile phone company offers two plans to its subscribers. When new subscribers sign up, they are asked to provide some demographic information. The mean yearly income of subscribers to Plan A is $75,917 while $71,400 is the mean income for subscribers to Plan B. The annual incomes of subscribers to Plan A and Plan B are recorded. The following output is obtained using the t-test function in RStudio: welch Two Sample t-test data: Plan A and Plan B t = 1. 0161, df = 37.964, p-value = 0.158 Alternative hypothesis: true difference in means is greater than 0 95 percent confidence interval: -2977 .756 Inf Sample estimates: mean of x mean of y 75917.0 71400 .0 Conduct an appropriate hypothesis test at a 5% level of significance to determine whether the income of those selecting Plan A is larger. Assume that the annual incomes for both groups are normally distributed. a. State the hypothesis statements. [1] b. State all the assumptions made. [1] c. State the test statistic including the degrees of freedom. [L] d. Write down the decision clearly stating the reason. [1]