Table:
0
A
B
C
D
E
1
State (class)
Vacator
Reason for change
Successor
Date of successors formal installation
2
Arkansas (2)
John L. McClellan (D)
Died November 28, 1977
Kaneaster Hodges, Jr. (D)
December 10, 1977
3
Montana (2)
Lee Metcalf (D)
Died January 12, 1978
Paul G. Hatfield (D)
January 22, 1978
4
Minnesota (1)
Hubert Humphrey (DFL)
Died January 13, 1978
Muriel Humphrey (D)
January 25, 1978
5
Alabama (3)
James Allen (D)
Died June 1, 1978
Maryon Pittman Allen (D)
June 8, 1978
6
Alabama (3)
Maryon Pittman Allen (D)
Successor elected November 7, 1978
Donald Stewart (D)
November 7, 1978
7
Minnesota (1)
Muriel Humphrey (DFL)
Successor elected November 7, 1978
David Durenberger (R)
November 8, 1978
8
Kansas (2)
James B. Pearson (R)
Resigned December 23, 1978
Nancy Kassebaum (R)
December 23, 1978
9
Mississippi (2)
James Eastland (D)
Resigned December 27, 1978
Thad Cochran (R)
December 27, 1978
10
Minnesota (2)
Wendell Anderson (DFL)
Resigned December 29, 1978
Rudy Boschwitz (R)
December 30, 1978
11
Wyoming (2)
Clifford Hansen (R)
Resigned December 31, 1978
Alan K. Simpson (R)
January 1, 1979

Questions and formulas:
Question: Who was the succesor that was formally installed on November 8, 1978?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,E1="November 8, 1978"),4))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E11,E2:E11="November 8, 1978"),4))
Level: medium