Where are my five friends?

Question

I was on a messaging app with four friends who were travelling all around the world.

Here are the messages:

Me: hi yall. where r u?

Message 1: i am in a big city in asia. Over 3 million people

Message 2: wow. i am in a big city, north america

Message 3: im in a big city, south america!

Message 4: well im in a big country in africa

Me: then where is dan?

Message response: a big city in europe. sleeping probably. Can u guess our locations precisely?

Me: Absolutely. You guys are in _ _ (four different cities)

and dan is in ___

What method did I use to get the answer?

Hint

One of those big cities is in Florida

Answer 1

I believe Dan is (quite literally) in:

GDANSK in Poland (GDANSK).

As for your other friends, they appear to be engaging in some wordplay/horseplay (delete as appropriate), aided by the lack of capitalisation throughout their messages...

When friend 1 says "i am in a big city in asia", they are referring to the city of XIAMEN (XIAMEN) in China (population 3.5m), since this contains the string 'IAM'.

When friend 2 says "i am in a big city, north america", they are referring to the city of MIAMI (MIAMI) in Florida in the USA (population c. 470,000), since this also contains the string 'IAM'.

When friend 3 says "im in a big city, south america", they are referring to the city of LIMA (LIMA) in Peru (population 10m), since this contains the string 'IM'.

When friend 4 says "im in a big country in africa", they might be referring to the city of TIMBUKTU (TIMBUKTU) in Mali, the 8th largest African country by area, since this city name contains the string 'IM'. (Alternatives might include Shubra el-KheIMa in Egypt, or just the country name, ZIMbabwe, although this is only the 26th largest country in Africa...)

Continuing this style of wordplay, 'Dan' is in:

The name of the Polish city 'GDANSK' (population approx. 470,000).

Answer 2

I'm not sure about this solution, but here is a possibility:

Friend in Asia:

Dhaka, Bangladesh (population about 9 million)

Friend in North America:

Phoenix, USA (population about 5 million, including metro area)

Friend in South America:

Santiago, Chile (population about 5 million)

Friend in Africa:

Abidjan, Ivory Coast (population about 4 million)

Friend in Europe:

Moscow, Russia (population about 12 million) (not sure about this one)

Method:

Assume that each message came with a local timestamp. This would allow each person's timezone to be determined. Then, find timezones for each continent where only one big city exists (with over 3 million population):

* The message from Asia came from time zone UTC+6, where the only large city in that time zone is Dhaka (Almaty is second with a a population of 2 million).
* The North American timezone was UTC-7, where the only large city is Phoenix (Denver is second with a population just under 3 million).
* In South America, it was UTC-4, where Santiago is the only large city (Caracas is second with a population of just under 3 million).
* In Africa, the time zone was UTC+0, where Abidjan is the only large city (Kumasi comes second with a population of 2 million). However, this assumes that Ivory Coast counts as a "big country in Africa". (What's considered big?)

Regarding the friend Dan in Europe, he was asleep and the reply came from someone else and we don't know his timezone. But given that the friend in Abidjan was awake at UTC+0, it would make sense that Dan was much further east, so the eastern-most large city in Europe is Moscow. St. Petersburg could work too, but it is west of Moscow.

Alternate answer: Dan is in bed. (It didn't say to name the city for Dan)