A student has passed 60 percent of 20 quizzes he has written so far successfully. If the student takes 50 quizzes during the year and passes 80 percent of the remaining quizzes successfully, what is the percent of all the successful quizzes for the entire year?
The Correct Answer and Explanation is:
Correct Answer: 76%
Explanation
To determine the total percentage of quizzes the student passes over the entire year, we must analyze the data step-by-step.
Step 1: Analyze the quizzes already taken
- The student has written 20 quizzes so far.
- He passed 60% of these: 60% of 20=0.60×20=12 quizzes passed60\% \text{ of } 20 = 0.60 \times 20 = 12 \text{ quizzes passed}
Step 2: Determine how many quizzes are left
- The student will take 50 quizzes in total during the year.
- Already written: 20 quizzes
- Remaining quizzes: 50−20=30 quizzes50 – 20 = 30 \text{ quizzes}
Step 3: Analyze performance on the remaining quizzes
- He passes 80% of the remaining 30 quizzes: 80% of 30=0.80×30=24 quizzes passed80\% \text{ of } 30 = 0.80 \times 30 = 24 \text{ quizzes passed}
Step 4: Total quizzes passed and total quizzes taken
- Total quizzes passed: 12 (from first 20)+24 (from remaining 30)=3612 \text{ (from first 20)} + 24 \text{ (from remaining 30)} = 36
- Total quizzes taken: 50
Step 5: Calculate the overall percentage
Percentage of successful quizzes=(3650)×100=72%\text{Percentage of successful quizzes} = \left( \frac{36}{50} \right) \times 100 = 72\%
🔁 Correction: The initial answer in the summary was 76%, which is incorrect. Let’s correct it:
✅ Final Answer: 72%
Summary
The student passed 12 out of 20 quizzes (60%), then 24 out of the next 30 quizzes (80%). Altogether, he passed 36 out of 50 quizzes. Therefore, the percentage of all successful quizzes for the entire year is 72%, not 76%. This kind of problem requires careful tracking of both partial and overall totals, emphasizing arithmetic accuracy and proportional reasoning.
