Jerry had an average score of 85 on his first eight quizzes. He had an
average score of 81 on his first nine quizzes. What score did he receive on
his ninth quiz?	Choose the correct choice.
A) 49  B) 51  C) 53  D) 55  E) 57
The sum of Jerry’s first 8 scores is 8 · 85 and the sum of his first 9 scores is 9 · 81, so he received   9 · 81 − 8 · 85 on his 9th quiz. You can do the arithmetic or note that the answer ends in a 9.   correct answer 49
<result>A</result>
Jerry had an average score of 85 on his first eight quizzes. He had an
average score of 81 on his first nine quizzes. What score did he receive on
his ninth quiz?