motion2020 wrote:
Set A has consecutive integers from 1 to n. If all integers in the set A are squared and then added, the result will be 2,470. How many integers are in the set A?
(A) 23
(B) 22
(C) 21
(D) 20
(E) 19
Sum of squares of first \(n\) consecutive numbers = \(\frac{n(n+1)(2n+1)}{6}\)
Check the option choices;
A. \(\frac{23(24)(47)}{6} = 4324\)B. \(\frac{22(23)(45)}{6} = 3795\)C. \(\frac{21(22)(43)}{6} = 3311\)D. \(\frac{20(21)(41)}{6} = 2870\)E. \(\frac{19(20)(39)}{6} = 2470\)Hence, option E