<span>Conditional probablility P(A/B) = P(A and B) / P(B). Here, A is sum of two dice being greater than or equal to 9 and B is at least one of the dice showing 6. Number of ways two dice faces can sum up to 9 = (3, 6), (4, 5), (4, 6), (5, 4), (5, 5), (5, 6), (6, 3), (6, 4), (6, 5), (6, 6) = 10 ways. Number of ways that at least one of the dice must show 6 = (1, 6), (2, 6), (3, 6), (4, 6), (5, 6), (6, 6), (6, 5), (6, 4), (6, 3), (6, 2), (6, 1) = 11 ways. Number of ways of rolling a number greater than or equal to 9 and at least one of the dice showing 6 = (3, 6), (4, 6), (5, 6), (6, 3), (6, 4), (6, 5), (6, 6) = 7 ways. Probability of rolling a number greater than or equal to 9 given that at least one of the dice must show a 6 = 7 / 11</span>
The vertex form of the equation for a parabola is ...
y = a(x -h)^2 +k
where the vertex is (h, k) and the value 'a' is a vertical scale factor.
The value of 'a' can be found by looking at the y-value of points ±1 either side of the vertex relative to the vertex. Here, the vertex y-value is +2 at x=3, and either side goes down 1 unit (to y=1) for 1 unit to the right or left. So, a = -1.
Using the values we've read from the graph for the vertex (h, k) = (3, 2) and the scale factor a = -1, we can write the equation as ...