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All questions of Alpha-Numeric Sequence Puzzle for Class 8 Exam

Directions: In each of the following questions find out which of the letter series follows the given rule.
Q. Number of letters skipped in between adjacent letters in the series is odd.
  • a)
    MPRUX
  • b)
    FIMRX  
  • c)
    EIMQV
  • d)
    BDHLR 
Correct answer is option 'D'. Can you explain this answer?

Rishika Tiwari answered
Let's analyze each option to determine which letter series has an odd number of letters skipped between adjacent letters.
Option 1: MPRUX
  • M to P: 2 letters skipped (N, O) — Even
  • P to R: 1 letter skipped (Q) — Odd
  • R to U: 2 letters skipped (S, T) — Even
  • U to X: 2 letters skipped (V, W) — Even
  • This series does not have all odd skips. So, not correct.
Option 2: FIMRX
  • F to I: 2 letters skipped (G, H) — Even
  • I to M: 3 letters skipped (J, K, L) — Odd
  • M to R: 4 letters skipped (N, O, P, Q) — Even
  • R to X: 5 letters skipped (S, T, U, V, W) — Odd
  • This series has a mix of odd and even skips. So, not correct.
Option 3: EIMQV
  • E to I: 3 letters skipped (F, G, H) — Odd
  • I to M: 3 letters skipped (J, K, L) — Odd
  • M to Q: 3 letters skipped (N, O, P) — Odd
  • Q to V: 4 letters skipped (R, S, T, U) — Even
  • This series also has a mix of odd and even skips. So, not correct.
Option 4: BDHLR
  • B to D: 1 letter skipped (C) — Odd
  • D to H: 3 letters skipped (E, F, G) — Odd
  • H to L: 3 letters skipped (I, J, K) — Odd
  • L to R: 5 letters skipped (M, N, O, P, Q) — Odd
  • All skips between letters in this series are odd.
Conclusion:
The correct answer is Option 4: BDHLR, as it is the only series where the number of letters skipped between adjacent letters is consistently odd.
 

In the series given below, how many 8’s are there each of which is exactly divisible by its immediate preceding as well as succeeding numbers?
​2 8 4 3 8 5 4 8 2 6 7 8 4 6 2 8 4 1 7 ? 
  • a)
    1  
  • b)
    2
  • c)
    3
  • d)
Correct answer is option 'C'. Can you explain this answer?

Understanding the Problem
In the given series, we need to identify the occurrences of the number 8 that are exactly divisible by both the numbers immediately before and after them.
Series Breakdown
The series is:
2, 8, 4, 3, 8, 5, 4, 8, 2, 6, 7, 8, 4, 6, 2, 8, 4, 1, 7
Identifying Relevant 8's
We will analyze each occurrence of the number 8:
- First 8 (2, 8, 4)
- Preceding number: 2
- Succeeding number: 4
- 8 is divisible by 2 (8 ÷ 2 = 4) and by 4 (8 ÷ 4 = 2).
- Valid 8
- Second 8 (3, 8, 5)
- Preceding number: 3
- Succeeding number: 5
- 8 is not divisible by 3 (8 ÷ 3 = 2.67) and not divisible by 5 (8 ÷ 5 = 1.6).
- Invalid 8
- Third 8 (4, 8, 2)
- Preceding number: 4
- Succeeding number: 2
- 8 is divisible by 4 (8 ÷ 4 = 2) and by 2 (8 ÷ 2 = 4).
- Valid 8
- Fourth 8 (6, 8, 4)
- Preceding number: 6
- Succeeding number: 4
- 8 is not divisible by 6 (8 ÷ 6 = 1.33) and by 4 (8 ÷ 4 = 2).
- Invalid 8
- Fifth 8 (2, 8, 4)
- Preceding number: 2
- Succeeding number: 4
- 8 is divisible by 2 and by 4.
- Valid 8
- Sixth 8 (4, 8, 1)
- Preceding number: 4
- Succeeding number: 1
- 8 is divisible by 4 and by 1.
- Valid 8
Conclusion
In total, we have three valid occurrences of 8 that meet the criteria. Therefore, the answer is 3.

Saket is 7 ranks ahead of Manoj in a class of 50. If Manoj’s rank is 17th from the last, what is Saket’s rank from the start?
  • a)
    25  
  • b)
    26
  • c)
    27
  • d)
    28 
Correct answer is option 'C'. Can you explain this answer?

Rahul Mehra answered
Manoj’s rank is 17th from the last.
Saket’s rank = 17 + 7 = 24th from the last.
No. of students ahead of Saket = 50 – 24 = 26
Saket’s rank from start = 26 + 1 = 27th 

Directions: Each of the following questions is based on the following alphabet – series:
A  B  C D E F G H I J K L M N O P Q R S T U V 
W X Y Z
Q. If the order of the English alphabet is reversed, then which letter would be exactly in the middle?
  • a)
    M
  • b)
    N  
  • c)
    L
  • d)
    None of these?
Correct answer is option 'D'. Can you explain this answer?

Shreya Sarkar answered
The new letter series obtained on reversing the order of the English alphabet is
Z Y X W V U T S R Q P O N M L K J I H G F E D C B A. 
Since the series has an even number of letters there is no such letter which lies exactly in the middle. 

Directions: Each of the following questions is based on the following alphabet – series:
A  B  C D E F G H I J K L M N O P Q R S T U V 
W X Y Z
Q. Which letter in the alphabet is as far from G as T is from M?
  • a)
    P
  • b)
    O  
  • c)
    M
  • d)
    N
Correct answer is option 'D'. Can you explain this answer?

Distance Calculation:
The distance between two letters in the alphabet can be calculated by counting the number of letters between them.

Distance between T and M:
T is 5 letters away from M in the alphabet. (M, N, O, P, Q, T)

Distance between G and the letter:
To find a letter that is as far from G as T is from M, we need to find a letter that is also 5 letters away from G.

Finding the letter:
Starting from G, we count 5 letters ahead which gives us the letter N. (G, H, I, J, K, N)
Therefore, the letter that is as far from G as T is from M is N.

In a queue, Ravi is 13th from the back Amar is 12th from the front. Hari is standing between the two. What should be the minimum number of boys standing in queue?
  • a)
    14  
  • b)
    15
  • c)
    16
  • d)
    17
Correct answer is option 'A'. Can you explain this answer?

Priya Pillai answered


Explanation:


- Given: Ravi is 13th from the back and Amar is 12th from the front.
- Let's assume there are 'x' boys in the queue.
- So, the position of Hari will be (x - 12) from the back and (x - 13) from the front.
- Since Hari is standing between Ravi and Amar, we have:
- (x - 13) - Ravi's position = Ravi's position - 1
- Ravi's position - (x - 12) = Amar's position - 1
- Solving the equations, we get Ravi's position as 13 and Amar's position as 14.
- Therefore, the minimum number of boys standing in the queue should be 14.

Therefore, the correct answer is option 'A' (14 boys).

Naresh ranks 5th in a class, Vikas is 8th from the last. If Raju is 6th after Naresh and Just in the middle of Naresh and Vikas. How many students are there in the class?
  • a)
    23  
  • b)
    24
  • c)
    25
  • d)
    26
Correct answer is option 'B'. Can you explain this answer?

Understanding the Rankings
Naresh ranks 5th in his class. This means there are 4 students ahead of him.
Vikas's Position
Vikas is 8th from the last. To find his actual position in the class, we need to know the total number of students. If we denote the total number of students as "N", then Vikas's position can be expressed as:
- Vikas's position = N - 7 (since he is 8th from the last)
Raju's Position
Raju ranks 6th after Naresh. Since Naresh is 5th, Raju would be:
- Raju's position = 5 + 6 = 11th
Middle Ranking
Raju is also stated to be in the middle of Naresh and Vikas. The middle position can be calculated as:
- Middle position = (Naresh's position + Vikas's position) / 2
This means:
- 11 = (5 + (N - 7)) / 2
Calculating the Total Students
To find N, we solve the equation:
1. Rearrange:
- 11 = (5 + N - 7) / 2
- 11 = (N - 2) / 2
2. Multiply both sides by 2:
- 22 = N - 2
3. Add 2 to both sides:
- N = 24
Conclusion
Therefore, the total number of students in the class is 24. Thus, the correct answer is option 'B'.

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