The slope of a line connecting the points (−6,−4),(0,−4),(1,−4),(4,−4) and (8,−4) is __
Four fair dice D1,D2,D3 and D4 each having six faces numbered 1, 2, 3, 4, 5 and 6 are rolled simultaneously. The probability that D4 shows a number appearing on one of D1,D2 and D3, is ?