Hello,
p=4845/116280=0.041666....
=================================
DIM k AS INTEGER, nFav AS LONG, nTot AS LONG, a AS INTEGER, b AS INTEGER, c AS INTEGER, d AS INTEGER
nTot = 0
nFav = 0
FOR k = 1 TO 17
FOR a = k + 1 TO 18
FOR b = a + 1 TO 19
FOR c = b + 1 TO 20
nFav = nFav + 1
PRINT nFav; k; a; b; c
NEXT c
NEXT b
NEXT a
NEXT k
nTot = 0
FOR a = 1 TO 20
FOR b = 1 TO 20
IF b <> a THEN
FOR c = 1 TO 20
IF c <> b AND c <> a THEN
FOR d = 1 TO 20
IF d <> c AND d <> b AND d <> a THEN
nTot = nTot + 1
PRINT nTot; a; b; c; d
END IF
NEXT d
END IF
NEXT c
END IF
NEXT b
NEXT a
PRINT "nFav="; nFav, "nTot="; nTot, "prob="; nFav / nTot
END
