Multiple choice

In a classroom, three students - Alice, Bob, and Charlie have different scores in mathematics test. Alice scored 60 marks, Bob scored 70 marks, and Charlie scored 80 marks. After re-evaluation, Alice's marks increased by 5%, Bob's marks increased by 10%, and Charlie's marks decreased by 10%. What is the approximate percentage increase in the average score of the these three students after the re-evaluation?

  1. 0.81%

  2. 0.75%

  3. 0.25%

  4. 0.96%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Initial average = (60+70+80)/3 = 70. New scores: Alice 60*1.05 = 63, Bob 70*1.10 = 77, Charlie 80*0.90 = 72. New sum = 63+77+72 = 212. New average = 212/3 = 70.666. Percentage increase = ((70.666-70)/70)*100 = 0.666/70 * 100 = 0.952%.

AI explanation

Using the average formula, the initial total score is 60 plus 70 plus 80, which equals 210. After re-evaluation, Alice gets 63 marks, Bob gets 77 marks, and Charlie gets 72 marks, making the new total 212. The initial average is 70 and the new average is 70.67, so the percentage increase is (0.67 divided by 70) multiplied by 100, which is approximately 0.96%.

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