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Consider two G.Ps. 2, 2 2 , 2 3 , …. and 4, 4 2 , 4 3 , … of 60 and n terms respectively. If the geometric mean of all the 60 + n terms is 8 225 ) 2 ( , then ∑ = n 1 k ) k – n ( k is equal to

1. 560
2. 1540
3. 1330
4. 2600

Correct answer: 1330

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