The correct answer is C
21, 37, 73, 137, ?, 381
31, 60, 118, 234, 466, ?
25 25 37.5 ? 328.125 1804.6875
10, ?, 50, 100, 250, 500
14, 17, 23, 32, ?, 59
13, 28, ?, 118, 238, 478
4097, ?, 4359, 4493, 4629, 4767
23 44 64 83 ? 118
...4, 5, 11, 34, 137, ?
What will come in place of the question mark (?) in the following series?
2.5, 6.5, 18.5, 54.5, 162.5, 486.5, ?
