3, 4, 7, 7, 13, 13, 21, 22, 31, 34, ?
Answer: Option B
Explanation:
The given sequence is a combination of two series :
I. 3, 7, 13, 21, 31, ? and II. 4, 7, 13, 22, 34
The pattern in I is + 4, + 6, + 8, + 10,.....
The pattern in II is + 3, + 6, + 9, + 12,.....
So, missing term = 31 + 12 = 43.
198, 194, 185, 169, ?
Answer: Option D
The pattern is - 4, - 9, - 16,.....i.e. - 22, - 32, - 42,.....
So, missing pattern = 169 - 52 = 169 - 25 = 144.
2, 3, 5,7,11,?, 17
Clearly, the given series consists of prime numbers starting from 2. So, the missing
term is the prime number after 11, which is 13.
6, 12, 21, ?, 48
Answer: Option A
The pattern is + 6, + 9, + 12, + 15, .....
So, missing term = 21 + 12 = 33.
Which term of the series 5, 10, 20, 40, ..... is 1280?
Clearly, 5 x 2 = 10, 10 x 2 = 20, 20 x 2 = 40,.....
So, the series is a G.P. in which a = 5 and r = 2.
Let 1280 be the rath term of the series.
Then, 5x2n-1 = 1280 2n-1 = 256 = 28 n - 1 = 8 n = 9.