The differences between two successive terms from the beginning are 7, 5, 7, 5, 7, 5. So, 40 is wrong.
Find the invalid no.from the following series 13, 18, 25, 30, 37, 40
Options:
(A) 30
(B) 35
(C) 40
(D) 47
(E) 50
(C)

The total of seven numbers = 7X20 = 140
The total of first 3 and last 3 numbers is = 3 X 14+3 X 19 = 99
So, the middle number is (140 - 99 ) = 41
The average of seven numbers is 20. The average of first three numbers is 14 and the average of last three numbers is 19. What is the middle number?
Options:
(A) 27
(B) 29
(C) 31
(D) 41
(E) 35
(D)

On dividing 531742 by 3 we get the remainder 1, so 1 should be subtracted
Find the least number must be subtracted from 531742 so that remaining no.is divisible by 3?
Options:
(A) 4
(B) 5
(C) 1
(D) 2
(E) 3
(C)