==== question 3 ====

# You want to take average for all variables but you realizedthat some variables have missing value
# before taking averages, you need to make sure that allobservations are taken from the same sets of
# observations (i.e. rows) where no variable ismissing

R programming problem

# Q3a. let's define a logical vector for non-missing rows, i.e.indicate TRUE for rows without any missing values,
# and FALSE for rows with missing values. Name the vector'nm'. Note that the length of nm will be the same as
# the number of rows in the original data df

# Q3b. count the number of non-missing rows in the data df, nameit 'count_nm'
# count_nm should be one number. Note that there is no sucha function 'count'.
# Think about how to count the number of non-missingrows.