Multiple choice

A class consists of $50$ students out of which $30$ are girls. The mean of marks scored by girls in a test is $73$ (out of $100$) and that of boys is $71$. Determine the mean score of the whole class.

  1. $72.2$
  2. $73.9$
  3. $75.6$
  4. $78$
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A Correct answer
Explanation

Total students = 50. Girls = 30, Boys = 20. Total marks = (30 * 73) + (20 * 71) = 2190 + 1420 = 3610. Mean = 3610 / 50 = 72.2.

AI explanation

Using the step-deviation or direct mean method, the total score for the girls is 30 * 73 = 2190, and the total score for the boys is 20 * 71 = 1420. The sum of all marks in the class is 2190 + 1420 = 3610. To find the overall mean, divide this total by the 50 students, yielding 3610 / 50 = 72.2.

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