Question 1164605
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The response from the other tutor is fine.  In that response, she uses y = ax^2 for the equation of the parabola with the given dimensions to find that a = 0.2; then she uses the formula f = 1/(4a) to find that the distance from the vertex to the focus is 1.25 inches.<br>
I and many students are familiar with a slightly different convention which of course leads to the same result.<br>
The basic standard formula for the equation of a parabola that I am familiar with is {{{y=(1/(4a))x^2}}}, where a is the distance from the vertex to the focus.  Using that to find the distance from the vertex to the focus directly...<br>
{{{1.8=(1/(4a))(3^2)}}}
{{{1.8=9/4a}}}
{{{7.2a=9}}}
{{{a=9/7.2=1.25}}}<br>
ANSWER: 1.25 inches<br>