Question Detail

In the series 2, 6, 18, 54, ... what will be the 8th term ?

4174
4150
4274
4374

Answer: Option D

Explanation:

We can see the given series is in G.P.
as 2*3 = 6, 6*3 = 18, 18*3 = 54
So a = 2 , r = 3
nth term in G.P. is
\begin{aligned}
ar^{n-1} \\
= 2*3{8-1} \\
= 2*3^7 \\
= 2*2187 = 4374
\end{aligned}

1. Look at this series: 22, 21, 23, 22, 24, 23, ... What number should come next?

Answer: Option A

Explanation:

Please look carefully at the series, its pattern is,
-1, +2, -1, +2, -1, so next will be +2
23+2 = 25

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. 3, 12, 27, 48, 75, 108,

Answer: Option D

Explanation:

Series is having pattern
\begin{aligned}
3*1^2, 3*2^2, 3*3^2, ......\\
\text{Next will be } 3*7^2 = 147
\end{aligned}

4. 20, 19, 17, (...) , 10, 5

Answer: Option D

Explanation:

Pattern in the series is -1, -2, .., .. , -5

So next term will be 17 - 3 = 14

5. 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}