All the numbers have equal number of digits, i.e. 8.
So, comparing the left most digits:
9 > 7 = 7 > 6 [1 mark]
Clearly, West Bengal has the highest population.
Now for Tamil Nadu and Madhya Pradesh:
We have to compare 72147030 and 72626809
Observing the lakhs place: 6 > 1
Therefore, Madhya Pradesh > Tamil Nadu [1 mark]
Overall order:
Descending order:
91276115 > 72626809 > 72147030 > 68548437
OR
West Bengal > Madhya Pradesh > Tamil Nadu > Rajasthan
[1 mark]