Six faces of a die are marked with number 1,−1,0,−2,2,3, and the die is thrown thrice. The probability that the sum of the numbers thrown is six, 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 ?
Each coefficient in the equation ax2+bx+c=0 is determined by throwing an ordinary die. Find the probability that the equation will have equal roots.