A professor gives two types of quizzes: objective and recall. He plans to give at least 18 quizzes this quarter.The student preparation time for an objective quiz is 12 minutes and for a recall quiz 36 minutes.The professor would like a student to spend at least 4 hours (240 minutes) preparing for these quizzes above and beyondthe normal study time.The average score on an objective quiz is 6, and on a recall quiz 4.The professor would like the students to average at least 88 points.It takes the professor 1.5 minutes to grade an objective quiz, and 2.5 minutes to grade a recall type quiz.How many of each type should he give in order to minimize his grading time?