Multiple choice

Mean of 10 numbers is 30. Later on it was observed that numbers 15, 23 are wrongly taken as 51, 32. The correct mean is – 10 सख्ंयाओं का औसत 30 है । बाद में पता चलता है कि उनमें से दो संख्यायें 15, 23 के स्थान पर गलती से 51, 32 लिख दी गयी थी। तो सही औसत है –

  1. 25.5

  2. 32

  3. 30

  4. 34.5
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A Correct answer
Explanation

Mean of 10 numbers is 30, so sum = 10 × 30 = 300. The wrong numbers 51 and 32 should be replaced by correct numbers 15 and 23. Correct sum = 300 - 51 - 32 + 15 + 23 = 300 - 83 + 38 = 255. Therefore correct mean = 255/10 = 25.5.

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