Direction: Find out the wrong number in the series.
1. 7, 8, 18, 57, 228, 1165, 6996
Answer: Option D
Explanation:
Let the given numbers be A, B, C, D, E, F, G.
Then, A, A x 1 + 1, B x 2 + 2, C x 3 + 3, D x 4 + 4, E x 5 + 5, F x 6 + 6 are the required numbers.
Clearly, 228 is wrong.
2. 1, 1, 2, 6, 24, 96, 720
Answer: Option B
Explanation:
Go on multiplying with 1, 2, 3, 4, 5, 6 to get next number.
So, 96 is wrong.
3. 64, 71, 80, 91, 104, 119, 135, 155
A. 71
B. 80
C. 104
D. 135
Answer: Option D
Explanation:
Go on adding 7, 9, 11, 13, 15, 17, 19 respectively to obtain the next number.
So, 135 is wrong.
4. 15, 16, 34, 105, 424, 2124, 12756
A. 16
B. 34
C. 105
D. 2124
Answer: Option D
Explanation:
[latex]{2}^{nd}[/latex] term = [latex]{1}^{st}[/latex] x 1 + 1 = 15 x 1 + 1 = 16
[latex]{3}^{rd}[/latex] term = [latex]{2}^{nd}[/latex] x 2 + 2 = 16 x 2 + 2 = 34
[latex]{4}^{th}[/latex] term = [latex]{3}^{rd}[/latex] x 3 + 3 = 34 x 3 + 3 = 105
[latex]{5}^{th}[/latex] term = [latex]{4}^{th}[/latex] x 4 + 4 = 105 x 4 + 4 = 424
[latex]{6}^{th}[/latex] term = [latex]{5}^{th}[/latex] x 5 + 5 = 424 x 5 + 5 = 2125
[latex]{6}^{th}[/latex] term should 2125 instead of 2124
5. 10, 26, 74, 218, 654, 1946, 5834
A. 26
B. 74
C. 218
D. 654
Answer: Option D
Explanation:
[latex]{2}^{nd}[/latex] term = [latex]{1}^{st}[/latex] x 3 - 4 = 10 x 3 - 4 = 26
[latex]{3}^{rd}[/latex] term = [latex]{2}^{nd}[/latex] x 3 - 4 = 26 x 3 - 4 = 74
[latex]{4}^{th}[/latex] term = [latex]{3}^{rd}[/latex] x 3 - 4 = 74 x 3 - 4 = 218.
[latex]{5}^{th}[/latex] term = [latex]{4}^{th}[/latex] x 3 - 4 = 218 x 3 - 4 = 650.
[latex]{5}^{th}[/latex] term must be 650 instead of 654