To find out what a percentage written as a fraction would look like, you first need to convert it into a decimal.
To convert a percentage to a decimal, you either need to divide the percentage by 100, or (my personal shortcut) just move the decimal point over two places to the left.
250% = 2.5
The decimal .5 is equivalent to 1/2, since 50 is half of 100.
250% written as a fraction (well, a mixed number, really) is 2 1/2.
Hope that helped =)
The vertex of the parabola is between the shortest line connecting its focus and directrix, so between (0, -4) and y = 4 is the point (0, 0), which is the vertex of the parabola. Also, this parabola faces downward.
The general formula for a parabola that faces downward is y = -4cx^2, where c is the distance from the vertex to either to focus or the parabola. Since c = 4, the equation is y = -16x^2, which is choice A.
Pythagorus Theorm
a sqr + b sqr = c sqr
25 sqr + 7 sqr = c sqr
625 + 49 = c sqr
625 + 49 = 674
c = sqr root of 674
c = 25.96 (rounded to 2dp)
The second choice is the correct one.
