Ans: Let’s assume population of Bangalore as 10 million and the day today is a working day for every age group

And age group wise population assumption would be

0–15 yrs: 30%; 15–25 yrs: 20%; 25–50 yrs: 30%; >50 yrs: 20%

Income wise population would be

Above poverty line: 75%

The people below poverty has negligible chance to use a watch, so I am eliminating this 25% population from every age group.

Now we have 75% of aforesaid % in every age group. As below poverty is eliminated 0–15 group mostly have school children and infants I assume 5% of them wearing watches today. So the count would be 2.25 million*5%=112500

15–25 age group have majority of higher education students who spend most of their time using mobile phones, so people using watches may be nearly 25% which gives 1.5 million*25%= 375000

25–50 groups have professionals working somewhere for their survival whose generation recently entered the smartphone culture. So most of them use watches. If out of this group, if 90% are couples, we will approximately have 20% housewives in it. As there is less chance of housewives wearing watches we can neglect it. The remaining 80% population say 90% wear watches, then count would be (80%*2.25 million)*90%=1620000

Coming to >50 group say 25% are working somewhere having 90% of them wearing watches again and in remaining 75% let 20% wear watches as we see many of our grandfathers wearing watches even in house. So count would be (25%*1.5 million)*90%+(75%*1.5 million)*20%= 562500

Total= sum of all these

=2.67 million wear watches