4 & 5 are wrong

\# Q4 \# Use the mean() function to compute the average \#\#\#\#\#\# lot frontage of the homes in this dataset. mean(!is.na(train\$LotFrontage)) \# Q5 \# Use the mean() function to compute the average \#\#\#\#\#\# lot frontage for a home with at least 1 fireplace. mean(train\$LotFrontage [train\$Fireplaces >=1] )