The monthly charge for water is 3 naira for the first 1000 litres and 5k for each additional 100 litres. A man used 3000 litres in a month. How much should he pay?

Answer 1

The man used a total of 3000 liters of water.

The first 1000 litres have a charge of 3 naira per litre, so the cost for the first 1000 litres is 3 * 1000 = <<3*1000=3000>>3000 naira.

The remaining 2000 litres are charged at a rate of 5 naira per 100 liters. Since there are 20 lots of 100 litres in 2000 litres, there will be a charge of 20 * 5 = <<20*5=100>>100 naira.

Therefore, the total charge for the man should be 3000 + 100 = <<3000+100=3100>>3100 naira. Answer: \boxed{3100}.