Multiple choice

The mean marks secured by $25$ student of a $ section\ A$ of $ X $ class is $47 $ that of $35$ students of $ section\ B$ is $51$ and that of $30$ students of $ section \ C$ is $ 53$ , the mean marks of all student of three section are

  1. $52.4$
  2. $55.4$
  3. $53.4$
  4. $50.55$
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D Correct answer
Explanation

The total sum of marks is (25 * 47) + (35 * 51) + (30 * 53) = 1175 + 1785 + 1590 = 4550. The total number of students is 25 + 35 + 30 = 90. The mean is 4550 / 90 = 50.55.

AI explanation

The combined mean formula is the total sum of all values divided by the total number of students. The total marks for section A is 25 times 47 (1175), for section B is 35 times 51 (1785), and for section C is 30 times 53 (1590). The sum of all marks is 1175 plus 1785 plus 1590, equaling 4550, and the total number of students is 25 plus 35 plus 30, equaling 90. Dividing 4550 by 90 gives the combined mean of 50.55.

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