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What is the mean of the squares of the first 20 natural numbers?

Options

  1. A151.5
  2. B143.5
  3. C65
  4. D72

Correct answer

B. 143.5

Step-by-step solution

aligned & 1^2+2^2+3^2+ .+20^2 & = n(n+1)(2 n+1) 6 [ array l 1^2+2^2+ .+n^2 = n(n+1)(2 n+1) 6 array ] & = 20 21 41 6 & Required mean value = 20 21 41 6 20 = 287 2 =143.5 . aligned

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