Directions (36-40) : What value comes in place of the question mark (?) in the following series?
30, 36, 46, 60, ?, 100
72
74
75
78
None of these
Solution
$30 + 6 = 36$
$36 + (6 + 4) = 36 + 10 = 46$
$46 + (10 + 4) = 46 + 14 = 60$
$60 + (14 + 4) = 60 + 18$ = 78
$78 + (18 + 4) = 78 + 22 = 100$