Alloy A contains iron and copper in ratio 4:5. Alloy B

625, 5, 125, 25, 25, ? , 5

21 23 26 ? 39 51

Identify the logic of the below given series and given answer.

Series I :: 1840, 1719, (P), 1694, 1890, 1665, 1921

96    111    131    ?       186     221

Choose the correct alternative

21: 3 ∷ 574: ?

A sequence {Tₙ} is defined by: Tₙ = a·n² + b·n + c for all positive integers n, where a, b, c are constants.

16     9     11    26     ?     912

The number of terms in the sequence 20, 25, 30, ….., 160 is:

70       191       47       216       ?       245

12 78 385 ? 4629 9260