Second,1.p1= 4 * 0.33 * (1-0.3) = 0.0756;
2. There are at most three tails, but at least four! So P2 =1-0.64 = 0.8704;
3. The probability that nobody likes it is 1+0.2-0.3-0.6=0.3.
Then P3 = (4 * 3/2) * 0.32 * (1-0.3) 2 = 0.2646.
3. Let the parabolic equation: y2 = 2 * p * x, then the focus is (p/2,0), and let the coordinates of a, b and c be (x 1, y 1), (y 2 2/2p, y2) and (y3 2/2p) respectively. From the barycentric coordinates (x 1+x2+x3)/3=p/2, (y 1+y2+y3)/3=0, x1= 3p/2-(x2+x3) = 3p/2-(Y2) x 1 = 1 1p/8- 10，y 1 =-(y2+y3) = p/2。 Substitute the A coordinate into the parabolic equation and get p=8.
That is, the parabolic equation is y 2 = 16x.
Let p(x, k*x,) substitute q(x,-1/k*x) into y 2 =16x to get p (16/k 2,16/k), q (/. The slope of the linear equation of PQ is (y2-y1)/(x2-x1) = k/(1-K2), and then the linear equation is determined by the coordinates of point P as (1-K2) y = k (x-650).