ALGO self doubt??

Question

the following questions are answered by me ,but are they right i have doubt on them  specially on last one please check .

1.the tightest lower bound on the number of comparisions in the worst case for comparision based sorting algo is of the order of  nlgn.

2..the tightest lower bound on the number of comparisions in the best case for comparision based sorting algo is of the order of

n

3..the tightest upper bound on the number of comparisions in the worst case for comparision based sorting algo is of the order of

n^2

4..the tightest upper bound on the number of comparisions in the best case for comparision based sorting algo is of the order of  n^2

Comments

2..the tightest lower bound on the number of comparisions in the best case for comparision based sorting algo is of the order of ?? how you predicted this as O(n) @eyeamgj 

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due to best case of insertion sort nd i think u took bubble sort??

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comparison based sorts...

Best of best case is O(n) ---- INSERTION sort --- lower bound of best case

worst of best case is O(n log n) ---- MERGE sort ---- lower bound of worst case

Best of worst case is O(n log n) ---- MERGE sort upper bound of best case

Worst of worst case is O(n²) --- QUICK sort / BUBBLE SORT etc ---- upper bound of worstcase