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. 1, 2, 5, 12, 27, 58, 121, ?

Answer: Option A

Explanation:

Pattern in the series is *2+1, *2+2, *2+3,.....

Term which replaces the question mark in the series is
121 * 2 + 6 = 248

2. 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}

3. Which fraction will come next, \begin{aligned} \frac{1}{2}, \frac{3}{4}, \frac{5}{8}, \frac{7}{16}, ? \end{aligned}

\begin{aligned} \frac{11}{32} \end{aligned}
\begin{aligned} \frac{9}{28} \end{aligned}
\begin{aligned} \frac{9}{30} \end{aligned}
\begin{aligned} \frac{9}{32} \end{aligned}

Answer: Option D

Explanation:

Numerators of the fractions in the given sequence are getting increased by 2, i.e. 1+2,3+2,5+2, so next will be 7+2 = 9

Denominators of the fractions in the series is getting doubled, 2*2 = 4, 4*2 = 8, 8*2 = 16, no next will be 16*2 = 32

So resulting fraction will be
\begin{aligned}
\frac{9}{32}
\end{aligned}

4. 1,6,15,(...),45,66,91

Answer: Option B

Explanation:

Pattern in the series is, +5, +9, .., .., +21, +25
So 4 is getting increased at every term addition.
Missing term in the series will be 15+(9+4)
= 15+13 = 28

5. 8, 9, 8, 7, 10, 9, 6, 11, 10, (...), 12

Answer: Option C

Explanation:

Please note that above sequence is containing 3 series
Series 1 : 8, 7, 6, (..)
Series 2 : 9, 10, 11, 12
Series 3 : 8, 9, 10

In series 1 pattern is -1. So missing term will be 6-1 = 5