There are two Classes A and B having 25 and 30 students respectively. In Class-A the highest score is 21 and…

There are two Classes A and B having 25 and 30 students respectively. In Class-A the highest score is 21 and lowest score is 17. In Class-B the highest score is 30 and lowest score is 22. Four students are shifted from Class-A to Class-B. Consider the following statements: 1. The average score of Class-B will definitely decrease. 2. The average score of Class-A will definitely increase. Which of the above statements is/are correct?
  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2

Solution

All scores in Class-A (17 to 21) are below the lowest score of Class-B (22). So the 4 students moved into Class-B carry lower marks than every existing Class-B student, definitely decreasing Class-B's average; Statement 1 is correct. For Class-A, the 4 departing students could have marks close to 21 or close to 17, so the change in Class-A's average is indeterminate; Statement 2 is incorrect.

Asked in: CSAT 2021

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