do it in R studio

7. (9pts) The data ToothGrowth in R records the length of odontoblasts in 60 guinea pigs. The variable len is the length of tooth, variable supp is the supplement type with VC being Vitamin C and OJ being Orange juice, and the variable dose is the dose in mg/day. Use pipeline to do the following: a) (3pts) Keep only two variables: len and supp b) (6pts) Find the mean len by each type of supplement. 8. (10pts) Given the data below with students' grades in homework, midterm exam and final exame, complete the following: Name Homework Midterm Final Abby 95 82 89 James 87 91 88 Tom 79 72 59 Jack 86 80 82 Kate 92 85 91 a) (4pts) Create a data frame for the table above, name the data frame as "studentdata" b) (6pts) Add a new column using pipeline to the end of the data, as overall. The overall is calculated by the following: if a student's homework grade>90, then the overall=(midterm+final)/2; otherwise, the overall =((midterm+final)/2)*1.1. Use the ifelse) function