Astudent has successfully passed 60 percent of the 20 quizzes he has written so far. if the student writes 50 quizzes during the year, and successfully passes 80 percent of the remaining quizzes, what is his percent success rate for all his quizzes for the entire year?

If there are 50 quizzes and the student has taken 20 so far, that means there are 30 remaining quizzes. Now we need to find the overall percentage if the student scores 60% on 20 quizzes and 80% on 30 quizzes.

To do this, we need to figure out what percentage of 50 is 20. 

or 40%

If 20 quizzes make up 40% of the total, then the remaining 30 quizzes make  up 60%. Now we need to multiply the scores earned by the max possible points out of 100.

0.6(40) + 0.8(60) = 72

The answer is 72%.