A tree diagram can be drawn for a clearer understanding. The branches of the tails can be ignored since we are not concerned about that. To find the probability along the branches, we just have to multiply the probabilities of each branch, giving you an answer of 1/128
The vertex of the parabola is at (5,3) and its focal length is 8/4 = 2.
Since it opens to the right, the directrix will be a vertical line 2 units to the left of the vertex, so its equation will be x=(5-2), or x=3
To find the value of x, you need to set up a proportion.This is the proportion you would set up:
2.5 x
---- = ------
3.75 60
x=40