The 550 Students Answered an Additional Question with the Following

The 550 students answered an additional question with the following results based on their rating of their instructor:
$$\begin{array} { | c | c | c | } \hline & \text { Very or Somewhat Effective } & \text { Very or Somewhat Ineffective } \\\hline \text { Final Grade } & & \\\hline \text { A } & 190 & 85 \\\hline \text { B } & 75 & 120 \\\hline \text { C } & 20 & 17 \\\hline \text { D } & 9 & 18 \\\hline \text { F } & 1 & 15 \\\hline\end{array}$$
$\begin{array} { ll l } \text {Rate the overall quality of your course. } \\&\text { Excellent } & 154 \\&\text { Good } & 187 \\&\text { Fair } & 71 \\&\text { Poor } & 138\\ \text { How effective was your instructor?} \\&\text { Very effective } & 75 \\&\text { Somewhat effective } & 220 \\&\text { Somewhat ineffective } & 155 \\&\text { Very ineffective } & 100\\ \text {How easy was it to read and understand the textbook? } \\&\text { Very easy } & 21 \\&\text { Easy } & 83 \\&\text { Hard } & 361 \\&\text { Very hard } & 85\end{array}$

Use the above results to answer the following questions:
Compute a point estimate of the proportion of all college statistic students who:

-What proportion of the students who rated their instructor as very or somewhat effective received a B or better in the class?

A) 0.345
B) 0.254
C) 0.482
D) 0.898
E) 0.644