rxs0005 wrote:

If the Sequence S has 100 terms what is the 83d term

1 Each term of S after the first term is 4 greater than the preceding term

2 The 84th term of S is twice the 82nd term

(1) \(a_n = a_1 + 4(n-1)\)

Without knowing \(a_1\), impossible to know \(a_{83}\)

(2) \(a_{84} = 2*a_{82}\)

All we know is that \(a_{83}\) is the average of these two or \(1.5 * a_{82}\), but this is still enough to calculate it.

(1+2) \(a_{84}=2*a_{82}\)

\(a_{84} = a_{82}+8\)

\(a_{82}+8=2*a_{82}\)

\(a_{82}=8\)

\(a_{83}=12\)

Sufficient

Answer is (C)
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