If the local time at Mumbai is 3 pm then what would be the local time at Kolkata?

If the local time at Mumbai is 3 p.m. then the time in Kolkata would be 4: 02 p.m. The difference is approximate of an hour and exactly two more minutes. This is calculated using the difference between their longitudes. Mumbai is 72 degree 50'E and Kolkata is 88 degrees 23'E. So the difference between them is 15.5 degree.

As

1 degree equals to 4 minutes. This means that for each degree of longitude, the local time differs by 4 minutes.

Therefore, converting 15.5 degrees into minutes, we get 62 minutes

which is two minutes more than an hour.

Adding 62 minutes into 3 p.m., we get 4: 02 p.m.