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All questions of Alpha-Numeric Sequence Puzzle for Class 7 Exam

Directions: Study the given number series and answer the questions based on it. 5 7 8 9 7 6 5 3 4 2 6 8 9 7 5 2 4 6 2 9 7 6 4 7 8 9 7 6
Q. How many times an even number is preceded by an odd number?
  • a)
    2
  • b)
    3
  • c)
    4
  • d)
    6
Correct answer is option 'D'. Can you explain this answer?

Sonia rao answered
Answer:

To find the number of times an even number is preceded by an odd number in the given series, we need to carefully observe the sequence and identify the pattern.

Observation:
- The series starts with the numbers 5, 7, 8, 9, which appear to be in ascending order.
- After the number 9, the series takes a downward trend and starts repeating a pattern of numbers.
- The pattern is as follows: 7, 6, 5, 3, 4, 2, 6, 8, 9, 7, 5, 2, 4, 6, 2, 9, 7, 6, 4, 7, 8, 9, 7, 6.
- As we can see, the pattern repeats itself after the number 6.

Analysis:
- We need to find the even numbers in the given series and check if they are preceded by an odd number.
- Let's list down the even numbers and their preceding numbers:
- 8 is preceded by 7 (odd)
- 6 is preceded by 9 (odd)
- 4 is preceded by 2 (even)
- 2 is preceded by 5 (odd)
- 6 is preceded by 4 (even)
- 8 is preceded by 7 (odd)
- 6 is preceded by 9 (odd)
- 4 is preceded by 6 (even)
- 6 is preceded by 7 (odd)

Counting:
- From the above analysis, we can observe that an even number is preceded by an odd number 6 times in the given series.

Therefore, the correct answer is option 'D' - 6.

Rohan is 12 ranks ahead of Ranjan in a class of 57. If Ranjan’s rank is 23 from the last, what is Rohan’s rank from the start?
  • a)
    21st
  • b)
    22nd
  • c)
    23rd
  • d)
    24th 
Correct answer is option 'C'. Can you explain this answer?

Madhavan Unni answered
Ranjan’s rank is 23rd from the last and Rohan is 12 ranks ahead of Ranjan.
No. of students ahead of Rohan
= 57 – (23 + 12) 
= 57 – 35 = 22
So, Rohan is 23rd from start. 

Directions: Study the given number series and answer the questions based on it. 5 7 8 9 7 6 5 3 4 2 6 8 9 7 5 2 4 6 2 9 7 6 4 7 8 9 7 6
Q. How many times two consecutive digits are odd numbers?
  • a)
    3
  • b)
    4
  • c)
    5
  • d)
    6
Correct answer is option 'D'. Can you explain this answer?

Hridoy Kapoor answered
Analysis:
To determine the number of times two consecutive digits are odd numbers, we need to carefully analyze the given number series. Let's break it down into smaller sections and observe the patterns.

Observations:
- The series starts with the numbers 5, 7, 8, 9.
- After the number 9, the series starts repeating itself.
- The repeating pattern is as follows: 7, 6, 5, 3, 4, 2, 6, 8, 9, 7, 5, 2, 4, 6, 2, 9, 7, 6, 4, 7, 8, 9, 7, 6.

Counting consecutive odd digits:
To count the number of times two consecutive digits are odd numbers, we need to identify all the pairs of consecutive odd digits in the series.

Pair 1: 5, 7
Pair 2: 7, 8
Pair 3: 8, 9
Pair 4: 9, 7
Pair 5: 7, 5
Pair 6: 5, 3
Pair 7: 3, 4
Pair 8: 4, 2
Pair 9: 2, 6
Pair 10: 6, 8
Pair 11: 8, 9
Pair 12: 9, 7
Pair 13: 7, 5
Pair 14: 5, 2
Pair 15: 2, 4
Pair 16: 4, 6
Pair 17: 6, 2
Pair 18: 2, 9
Pair 19: 9, 7
Pair 20: 7, 6
Pair 21: 6, 4
Pair 22: 4, 7
Pair 23: 7, 8
Pair 24: 8, 9
Pair 25: 9, 7
Pair 26: 7, 6

Therefore, there are a total of 26 pairs of consecutive odd digits in the given number series.

Conclusion:
The correct answer is option 'D' as there are 26 instances of two consecutive odd digits in the series.

Chapter doubts & questions for Alpha-Numeric Sequence Puzzle - Science Olympiad Class 7 2025 is part of Class 7 exam preparation. The chapters have been prepared according to the Class 7 exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Class 7 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.

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