A hint to get started
Split a parent–child–parent block by its table
Mr and Mrs Tan have a son David and invite 6 guests for dinner. Before dinner, all 9 diners stand in a straight row for a group photo. Find the arrangements if
(i) all 9 diners may stand anywhere, mark
(ii) the Tan family members must be separated. marks
The diners then sit at two round tables, a five-seater and a smaller four-seater. Find the arrangements if
(iii) anyone may sit at either table, marks
(iv) David must sit between his parents at either table. marks
[2011/SAJC/II/6]
CJC · Review problems · Question 15
The two tables are distinguished by size; sum the two possible placements of the family block.