Insert the missing number in the given series: 165,195,255,285,345,(.......) The options given are : A.375 B.420 C.435 D.390
(A) is the correct option.
clearly,
195-165=30
255-195=60
285-255=30
345-285=60
therefore if the next number is x, then
x-345=30
i.e., x=345+30=375
hence, the ans is 375.