Answer :
So for this you must ignore the student with 2.
then you see how many in order
1-6 siblings
1-5 siblings
2-3 siblings
add up the left coulumn to get 4 people have more than 3 siblings
then you see how many in order
1-6 siblings
1-5 siblings
2-3 siblings
add up the left coulumn to get 4 people have more than 3 siblings