Permutations & Combinations
Multinomial sequence counting
nta_pyq_2025_apr
Grade 12
Question:
The number of sequences of ten terms, whose terms are either 0 or 1 or 2, that contain exactly five 1 s and exactly three 2 s, is equal to
Step-by-Step Solution
Key Concept: Use multinomial counting with exactly five$1$s and prescribed counts for the other symbols.
11111 222 00$(3)$No. of$sequences = 10$! 5!3!2! = 2520 Note: Sequence can start with 0.
Correct Answer: 3