After M students took a test, the average score was 72%. If the test has 50 questions, what is the least number of questions that the next student has to get right to bring the average score up to 75%?  Choose the correct option.
A) 1.5M + 36
B) 72 - 1.5M
C) 1.5M + 37.5
D) 0.75 + 1.5M
E) 1.5M + 0.72
The total number of correct answers for M students is (0.72)*50*M=36*M   For an average of 75%: (total correct answers) / (M+1) = 0.75*50= 
<gadget id="calculator">0.75*50</gadget>
<output>37.5</output>
37.5   Let x be the number of correct answers for the next student.   (x + 36M) / M+1= 37.5   x + 36M= 37.5M+37.5   x = 1.5M + 37.5   The answer is 1.5M + 37.5.
<result>C</result>
After M students took a test, the average score was 72%. If the test has 50 questions, what is the least number of questions that the next student has to get right to bring the average score up to 75%?