c. To create a function called st.err()=sd(x)/sqrt(length(x)) to find the standard error in SUB1, SUB2, and SUB3.
3. Create a vector TOTAL_SUM that hold the value of V1, V2, and V3 using sapply().
6. Create a function f(x,y)=x/y where x is V1 and y is V2. Use mapply() to compute this function.
7. Practice all apply functions on “Seatbelts” data set given in R.
