1.
Texas Instruments technical mcq question, verified with a worked answer. Free to practise - no sign-up.
Missing number**
In the given series of numbers:
3, 4,4, 6, 8, 10, 9, 12, 15, ?
Identify the missing number (?) to complete the respective series.
Show answer & explanation
Answer: B. B) 12
The series interleaves three arithmetic progressions: (3, 6, 9, 12), (4, 8, 12, 16), and (4, 10, 15, ...). The 10th term follows the first progression: 9 + 3 = 12.
Step-by-step Derivation:
Step 1: First interleaved sequence (terms 1, 4, 7, 10): 3, 6, 9, ... (+3 each time).
Step 2: Second interleaved sequence (terms 2, 5, 8): 4, 8, 12, ... (+4 each time).
Step 3: Third interleaved sequence (terms 3, 6, 9): 4, 10, 15, ...
Step 4: The 10th term belongs to the first sequence: 9 + 3 = 12.