APTITUDE | ARITHMATICAL | ODD MAN OUT AND SERIES | FIND OUT THE WRONG NUMBER IN EACH SEQUENCE 2

DIRECTIONS : Find out the wrong number in the series

6.	3, 7, 15, 27, 63, 127, 255
	A.   7	B.   15
	C.   27	D.   63

Solution

27. Go on multiplying the number by 2 and adding 1 to it to get the next number. So 27 is wrong.

7.	2880, 480, 92, 24, 8, 4, 4
	A.   480	B.   92
	C.   24	D.   8

Solution

92. Go on dividing by 6, 5, 4, 3, 2, 1 respectively to obtain the next number. Clearly, 92 is wrong.

8.	445, 221, 109, 46, 25, 11, 4
	A.   221	B.   109
	C.   46	D.   25

Solution

46. Go on subtracting 3 dividing the result by 2 to obtain the next number. Clearly, 46 is wrong.

9.	7, 8, 18, 57, 228, 1165, 6996
	A.   8	B.   18
	C.   57	D.   228

Solution

228. Let the given numbers be A, B, C, D, E, F, G. Then A, Ax1, Bx2+2, Cx3+3, Dx4+4, Ex5+5 ... and so on. are the required numbers. Clearly, 228 is wrong.

10.	1, 3, 10, 21, 64, 129, 356, 777
	A.   10	B.   21
	C.   64	D.   356

Solution

356. Ax2+1, Bx3+1, Cx2+1, Dx3+1 and so on. So, 356 is wrong.