Step 1: Understanding the partnership.
The existing partnership ratio is 9 : 6 : 5 : 5. With 'N' joining the partnership, the new ratio is to be shared among J, K, L, M, and N.
Step 2: Analyzing the options.
(A) 3 : 4 : 2 : 1 : 5: Correct — This is the correct answer. The new profit-sharing ratio includes 'N', who gets a 20% share, and the rest of the partners share the remaining 80% in the ratio 3 : 4 : 2 : 1.
(B) 9 : 6 : 5 : 5 : 5: Incorrect — This is the original ratio and does not reflect 'N' joining the partnership.
(C) 8 : 6 : 4 : 2 : 5: Incorrect — This does not match the new agreed-upon ratio.
(D) 6 : 8 : 4 : 2 : 5: Incorrect — This does not match the expected results either.
Step 3: Conclusion.
The correct answer is (A) 3 : 4 : 2 : 1 : 5, as this correctly represents the new profit-sharing ratio after 'N' joins.