Çözüldü Average (Arithmetic Mean)

https://i.ibb.co/YdvYh5J/Statistics.png
https://www.worldwisetutoring.com/w.../SAT-Subject-Math-Level-1-Practice-Test-1.pdf
(Page 11, Question 27)

D

If the average of the 5 original scores was 83, then the sum of those 5 scores was 5 × 83 = 415. When each score is increased by 2, the sum goes up to 415 + 5·2 = 425, one-fifth of which is 425 / 5 = 85. So the new average is 85 and statement I is true.

Statement II, however, is not true because if both the lowest and highest scores go up by the same amount, the difference between those scores remains the same. So I is true and II is not, and the answer is either (A) or (D).

What about III? To find the lowest score that one of the 5 students can get, imagine that after the increase the other 4 students all get perfect 100s. Four 100s add up to 400, which leaves 425 – 400 = 25 for the fifth and lowest possible score for the 5 students. III is true.

https://www.worldwisetutoring.com/w...-Practice-Test-1-Answers-and-Explanations.pdf
(Page 8)