Table:
0
A
B
C
D
E
1
Task No.
Date given
Head of Household
Hand Grenade User
Hand Grenade Recipient
2
1
December 10, 2009 (Day 68)
Paul Jake
Carol
Hermes
3
2
December 19, 2009 (Day 77)
Rica
Cathy
Patrick
4
3
December 26, 2009 (Day 84)
Cathy
Johan
Rica
5
4
January 2, 2010 (Day 91)
Paul Jake
Jason
Self Automatic Nomination
6
5
January 10, 2010 (Day 99)
Kath
Jason
Tibo
7
6
January 17, 2010 (Day 106)
Mariel
Hermes
Self Automatic Nomination
8
7
January 22, 2010 (Day 111)
Tibo
Tibo
Jason (Automatic Nomination)

Questions and formulas:
Question: What date was Rica head of household?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,C1="rica"),2))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E8,C2:C8="rica"),2))
Level: medium
Question: What is the latest task number for which Cathy is head of household?
Formula: MAXIFS(A1,C1,"cathy")
Formula2: MAXIFS(A2:A8,C2:C8,"cathy")
Level: easy
Question: Who is the head of household for task number 7?
Formula: LET(query1,SUMMARIZE(C1,SUMX(A1)),FILTER(query1,CHOOSECOLS(query1,2)=7))
Formula2: LET(query1,SUMMARIZE(C2:C8,SUMX(A2:A8)),FILTER(query1,CHOOSECOLS(query1,2)=7))
Level: hard
Question: Which task had Cathy as the hand grenade user?
Formula: SUMIFS(A1,D1,"cathy")
Formula2: SUMIFS(A2:A8,D2:D8,"cathy")
Level: easy
Question: What is the task number on January 22, 2010 (day 111)?
Formula: SUMIFS(A1,B1,"january 22, 2010 (day 111)")
Formula2: SUMIFS(A2:A8,B2:B8,"january 22, 2010 (day 111)")
Level: easy