Question Detail

In the series 3, 9, 15.. what will be the 21st term ?

Answer: Option A

Explanation:

We can judge that it is A.P.
With 6 as difference
nth term in A.P. = a+(n-1)d
a= 3, n = 21, d = 6
So, 21st term will be = 3+(20)6 = 123

1. 13, 32, 24, 43, 35, (...), 46, 65, 57, 76

Answer: Option B

Explanation:

There are two series in this sequence
Series 1: 13, 24, 35, 46, 57
Series 2: 32, 43, (..), 65, 76

The pattern it is following is +11
Missing number will be 43 + 11 = 54

2. 4, 10, (?), 82, 244, 730

Answer: Option B

Explanation:

Each number in the series is the preceding number multiplied by 3 and then decreased by 2.

3. 2,15,41,80, ? . Complete the series.

Answer: Option B

Explanation:

Pattern is +13,+(13*2), +(13*3)
Next will be +(13*4) = 80+52 = 132

4. Complete the series 2,2,5, 13,28,....

Answer: Option C

Explanation:

\begin{aligned}
\text{Pattern is }\\
+1^2-1, +2^2-1, +3^2-1,+4^2-1 \\
5^2-1 = 28 + 24 \\
= 52
\end{aligned}

5. 5, 6, 7, 8, 10, 11, 14, (...) ?

Answer: Option D

Explanation:

Please check that given sequence consists of two series

Series 1: 5, 7, 10, 14
Series 2: 6, 8, 11, ...

In series 2 pattern is +2, +3, Next will be +4
So required number in the series will be 11+4 = 15