What is the sixtieth term in the following sequence? 1, 2, 4, 7, 11, 16, 22...
(A) 1,671 (B) 1,760 (C) 1,761 (D) 1,771 (E) 1,821
(A) 1,671 (B) 1,760 (C) 1,761 (D) 1,771 (E) 1,821
Let's look for a pattern.sukhman wrote:What is the sixtieth term in the following sequence? 1, 2, 4, 7, 11, 16, 22...
(A) 1,671 (B) 1,760 (C) 1,761 (D) 1,771 (E) 1,821
term1 = 1
term2 = 1 + 1
term3 = 1 + 1 + 2
term4 = 1 + 1 + 2 + 3
term5 = 1 + 1 + 2 + 3 + 4
term6 = 1 + 1 + 2 + 3 + 4 + 5
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.
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term60 = 1 + 1 + 2 + 3 + 4 + . . . 58 + 59
So, we need to evaluate 1 + 2 + 3 + 4 + . . . 58 + 59
Nice rule: The sum of the integers from 1 to n inclusive = (n)(n+1)/2
So, the sum of the integers from 1 to 59 = (59)(60)/2 = 1770
This means that term60 = 1 + 1770
= 1771
= D
Cheers,
Brent
