Multiple choice general knowledge math & puzzles

From a book, a number of consecutive pages are missing. The sum of the page numbers of these pages is 9808. The Question: Which pages are missing?

  1. 292-322

  2. 291-322

  3. 291-321

  4. 290-320

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let the missing pages be n to m. The sum is (m-n+1)(n+m)/2 = 9808. For pages 291-322, number of pages is 32. Sum = 32 * (291+322)/2 = 16 * 613 = 9808. This matches the given sum.