33688, 400, 256, 184, 148, ?
A120
B125
C130
D136
Answer: C
Explanation:
$\begin{array}{cc}
Pattern & Series \\[4px]
688 & 688 \\[4px]
688 - 576/2 & 400 \\[4px]
400 - 288/2 & 256 \\[4px]
256 - 144/2 & 184 \\[4px]
184 - 72/2 & 148 \\[4px]
148 - 36/2 & 130 &\checkmark\\[4px]
\end{array}$
347, 9, 21, 67, 273, ?
A1271
B1375
C1371
D1365
Answer: C
Explanation:
$\begin{array}{cc}
Pattern & Series \\[4px]
7 & 7 \\[4px]
7 × 1 + 2 & 9 \\[4px]
9 × 2 + 3 & 21 \\[4px]
21 × 3 + 4 & 67 \\[4px]
67 × 4 + 5 & 273 \\[4px]
273 × 5 + 6 & 1371 &\checkmark\\[4px]
\end{array}$
3512, 35, 51, 90, ?, 207
A121
B135
C171
D142
Answer: D
Explanation:
$\newcommand\pad[1]{\rlap{#1}\phantom{120}}
\begin{array}
\pad{12} &&\pad{25} &&\pad{51} &&\pad{90} &&\pad{?} &&\pad{207}\\[4px]
&\pad{13} &&\pad{+26} &&\pad{+39} &&\color{red}{+52} &&\pad{+65}
&& \Leftarrow\text{1st Diff.} \\[4px]
\end{array}$
367, 11, 20, 45, 94, 215, ?
A321
B358
C371
D384
Answer: D
Explanation:
$\newcommand\pad[1]{\rlap{#1}\phantom{120}}
\begin{array}
\pad{7} &&\pad{11} &&\pad{20} &&\pad{45} &&\pad{94} &&\pad{215} &&\pad{?}\\[4px]
&\pad{+2^2} &&\pad{+3^2} &&\pad{+5^2} &&\pad{+7^2} &&\pad{+11^2}&&\color{red}{+13^2}
&& \Leftarrow\text{1st Diff.} \\[4px]
\end{array}$
37640, 400, 280, ?, 190, 175
A220
B258
C221
D254
Answer: A
Explanation:
$\newcommand\pad[1]{\rlap{#1}\phantom{120}}
\begin{array}
\pad{640} &&\pad{400} &&\pad{280} &&\pad{?} &&\pad{190} &&\pad{175}\\[4px]
&\pad{-240} &&\pad{-120} &&\color{red}{-60} &&\pad{-30} &&\pad{-15}
&& \Leftarrow\text{1st Diff.} \\[4px]
\end{array}$
3825, 15, 20, 37.5, 85, 225, ?
A650
B658
C620
D690
Answer: D
Explanation:
$\begin{array}{cc}
Pattern & Series \\[4px]
25 & 25 \\[4px]
25 × 0.5 + 2.5 & 15 \\[4px]
15 × 1 + 5 & 20 \\[4px]
20 × 1.5 + 7.5 & 37.5 \\[4px]
37.5 × 2 + 10 & 85 \\[4px]
85 × 2.5 + 12.5 & 225 \\[4px]
225 × 3 + 15 & 690 &\checkmark\\[4px]
\end{array}$
397, 8, 20, 69, 292, ?
A1452
B1458
C1485
D1490
Answer: C
Explanation:
$\begin{array}{cc}
Pattern & Series \\[4px]
7 & 7 \\[4px]
7 × 1 + 1^2 & 8 \\[4px]
8 × 2 + 2^2 & 20 \\[4px]
20 × 3 + 3^2 & 69 \\[4px]
69 × 4 + 4^2 & 292 \\[4px]
292 × 5 + 5^2 & 1485 &\checkmark\\[4px]
\end{array}$
4016, 64, 224, ?, 1680, 3360
A658
B688
C675
D680
Answer: C
Explanation:
$\begin{array}{cc}
Pattern & Series \\[4px]
16 & 16 \\[4px]
16 × 4 & 64 \\[4px]
64 × 3.5 & 224 \\[4px]
224 × 3 & 672 &\checkmark\\[4px]
672 × 2.5 & 1680 \\[4px]
1680 × 2 & 3360 \\[4px]
\end{array}$