Table:
0
A
B
C
D
E
1
Episode
Broadcast date
Run time
Viewers (in millions)
Archive
2
" Episode 1 "
3February1968
24:53
7.2
16mm t/r
3
" Episode 2 "
10February1968
24:38
6.8
16mm t/r
4
" Episode 3 "
17February1968
24:34
7.0
Only stills and/or fragments exist
5
" Episode 4 "
24February1968
24:50
8.4
16mm t/r
6
" Episode 5 "
2March1968
24:19
8.0
16mm t/r
7
" Episode 6 "
9March1968
24:41
8.3
16mm t/r

Questions and formulas:
Question: how many archive were when run time is 24:34
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,C1="24:34"),5))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E7,C2:C7="24:34"),5))
Level: medium
Question: what is all the  broadcast date when viewers were 8.4 millions
Formula: LET(query1,SUMMARIZE(B1,SUMX(D1)),FILTER(query1,CHOOSECOLS(query1,2)=8.4))
Formula2: LET(query1,SUMMARIZE(B2:B7,SUMX(D2:D7)),FILTER(query1,CHOOSECOLS(query1,2)=8.4))
Level: hard
Question: how many episode have 8.4 millions  viewer.
Formula: ROWS(UNIQUE(FILTER(A1, D1=8.4)))
Formula2: ROWS(UNIQUE(FILTER(A2:A7, D2:D7=8.4)))
Level: medium