Multiple choice

In a Physics test, the average marks of girls in a class is 40. If the average marks of first 20 girls is 50 and that of the remaining girls is 20, then the total number of girls in the class is: 1.30 2.40 3.25 4.45

  1. 1

  2. 2

  3. 3

  4. 4
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A Correct answer
Explanation

Let total girls be N. Total marks = 40N. First 20 girls total = 20 * 50 = 1000. Remaining girls (N-20) total = (N-20) * 20. So, 40N = 1000 + 20N - 400. 20N = 600, N = 30.

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